- Deprecated: Should now use avoidClientSideDownload in place of

`avoidClientSide` (config for `ext-server_opensave.js`).
- Enhancement: Added `avoidClientSideOpen` config for
    `ext-server_opensave.js`
- npm: Update devDeps (including switching from deprecate opn-cli
    package to open-cli)

docs/Contributing.md

@@ -5,6 +5,7 @@
   - `Security fix: `
   - `Known regression: `
   - `Breaking change: `
+  - `Deprecated:`
   - `Compatibility fix: `
   - `Fix: `
   - `Fix (<component>): ` - Component may be an extension, locale, etc.