[Feature] Text-In-Stage support & missing IVoiceChannel properties (#2610)

* initial commit

* add a check for voice/stage channels in `PinAsync`

* moar refactoring

* Update IStageChannel.cs

* forgot about mocked. again.

src/Discord.Net.Core/Entities/Channels/IStageChannel.cs

@@ -8,14 +8,6 @@ namespace Discord
     /// </summary>
     public interface IStageChannel : IVoiceChannel
     {
-        /// <summary>
-        ///     Gets the topic of the Stage instance.
-        /// </summary>
-        /// <remarks>
-        ///     If the stage isn't live then this property will be set to <see langword="null"/>.
-        /// </remarks>
-        string Topic { get; }
-
         /// <summary>
         ///     Gets the <see cref="StagePrivacyLevel"/> of the current stage.
         /// </summary>

src/Discord.Net.Core/Entities/Channels/IVoiceChannel.cs

@@ -7,7 +7,7 @@ namespace Discord
     /// <summary>
     ///     Represents a generic voice channel in a guild.
     /// </summary>
-    public interface IVoiceChannel : IMessageChannel, INestedChannel, IAudioChannel, IMentionable
+    public interface IVoiceChannel : ITextChannel, IAudioChannel
     {
         /// <summary>
         ///     Gets the bit-rate that the clients in this voice channel are requested to use.
@@ -31,44 +31,6 @@ namespace Discord
         /// </summary>
         VideoQualityMode VideoQualityMode { get; }
 
-        /// <summary>
-        ///     Bulk-deletes multiple messages.
-        /// </summary>
-        /// <example>
-        ///     <para>The following example gets 250 messages from the channel and deletes them.</para>
-        ///     <code language="cs">
-        ///     var messages = await voiceChannel.GetMessagesAsync(250).FlattenAsync();
-        ///     await voiceChannel.DeleteMessagesAsync(messages);
-        ///     </code>
-        /// </example>
-        /// <remarks>
-        ///     This method attempts to remove the messages specified in bulk.
-        ///     <note type="important">
-        ///         Due to the limitation set by Discord, this method can only remove messages that are posted within 14 days!
-        ///     </note>
-        /// </remarks>
-        /// <param name="messages">The messages to be bulk-deleted.</param>
-        /// <param name="options">The options to be used when sending the request.</param>
-        /// <returns>
-        ///     A task that represents the asynchronous bulk-removal operation.
-        /// </returns>
-        Task DeleteMessagesAsync(IEnumerable<IMessage> messages, RequestOptions options = null);
-        /// <summary>
-        ///     Bulk-deletes multiple messages.
-        /// </summary>
-        /// <remarks>
-        ///     This method attempts to remove the messages specified in bulk.
-        ///     <note type="important">
-        ///         Due to the limitation set by Discord, this method can only remove messages that are posted within 14 days!
-        ///     </note>
-        /// </remarks>
-        /// <param name="messageIds">The snowflake identifier of the messages to be bulk-deleted.</param>
-        /// <param name="options">The options to be used when sending the request.</param>
-        /// <returns>
-        ///     A task that represents the asynchronous bulk-removal operation.
-        /// </returns>
-        Task DeleteMessagesAsync(IEnumerable<ulong> messageIds, RequestOptions options = null);
-
         /// <summary>
         ///     Modifies this voice channel.
         /// </summary>

src/Discord.Net.Core/Entities/Channels/VoiceChannelProperties.cs

@@ -1,26 +1,33 @@
-namespace Discord
+using System;
+
+namespace Discord;
+
+/// <summary>
+///     Provides properties that are used to modify an <see cref="IVoiceChannel" /> with the specified changes.
+/// </summary>
+public class VoiceChannelProperties : TextChannelProperties
 {
     /// <summary>
-    ///     Provides properties that are used to modify an <see cref="IVoiceChannel" /> with the specified changes.
+    ///     Gets or sets the bitrate of the voice connections in this channel. Must be greater than 8000.
     /// </summary>
-    public class VoiceChannelProperties : GuildChannelProperties
-    {
-        /// <summary>
-        ///     Gets or sets the bitrate of the voice connections in this channel. Must be greater than 8000.
-        /// </summary>
-        public Optional<int> Bitrate { get; set; }
-        /// <summary>
-        ///     Gets or sets the maximum number of users that can be present in a channel, or <c>null</c> if none.
-        /// </summary>
-        public Optional<int?> UserLimit { get; set; }
-        /// <summary>
-        ///     Gets or sets the channel voice region id, automatic when set to <see langword="null"/>.
-        /// </summary>
-        public Optional<string> RTCRegion { get; set; }
+    public Optional<int> Bitrate { get; set; }
+    /// <summary>
+    ///     Gets or sets the maximum number of users that can be present in a channel, or <c>null</c> if none.
+    /// </summary>
+    public Optional<int?> UserLimit { get; set; }
+    /// <summary>
+    ///     Gets or sets the channel voice region id, automatic when set to <see langword="null"/>.
+    /// </summary>
+    public Optional<string> RTCRegion { get; set; }
 
-        /// <summary>
-        ///     Get or sets the video quality mode for this channel.
-        /// </summary>
-        public Optional<VideoQualityMode> VideoQualityMode { get; set; }
-    }
+    /// <summary>
+    ///     Get or sets the video quality mode for this channel.
+    /// </summary>
+    public Optional<VideoQualityMode> VideoQualityMode { get; set; }
+
+    /// <remarks>
+    ///     Not supported in voice channels
+    /// </remarks>
+    /// <inheritdoc cref="TextChannelProperties.Topic"/>
+    public new Optional<string> Topic { get; }
 }