separate svgcanvas from svgedit

now you can use directlt svgcanvas. see readme.md

* configure workspaces
* move svgcanvas to packages folder
* move utils to common and paint to svgcanvas
* make svgcanvas a dependency of svgedit
* update deps
* workspaces requires npm 7 at least so the ci needs a new node version
* update github actions to V3
* update snapshots using custom svg exports
* remove unmaintained cypress snapshot plugin
* new github action to add coverage in PR
* Update onpushandpullrequest.yml
* svgcanvas v7.1.6

cypress/__svgSnapshots__/scenario-check tool_text_change_opacity.svg

@@ -0,0 +1,12 @@
+<svg width="640" height="480" xmlns="http://www.w3.org/2000/svg" xmlns:svg="http://www.w3.org/2000/svg">
+ <g class="layer">
+  <title>Layer 1</title>
+  <text fill="#bf0000" font-family="Serif" font-size="34" font-style="italic" font-weight="bold" id="svg_1" stroke="#0000bf" text-anchor="middle" transform="matrix(1 0 0 1 0 0)" x="200" xml:space="preserve" y="200">AB</text>
+  <text fill="#000000" filter="url(#svg_2_blur)" font-family="Serif" font-size="24" id="svg_2" opacity="0.5" stroke="#000000" stroke-width="0" text-anchor="middle" x="245" xml:space="preserve" y="245">AB</text>
+ </g>
+ <defs>
+  <filter height="200%" id="svg_2_blur" width="200%" x="-50%" y="-50%">
+   <feGaussianBlur in="SourceGraphic" stdDeviation="5"/>
+  </filter>
+ </defs>
+</svg>