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__/scenario5-check tool_line_change_opacity.svg

@@ -0,0 +1,11 @@
+<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>
+  <line class="svg_1_class" fill="none" filter="url(#svg_1_id_blur)" id="svg_1_id" opacity="0.5" stroke="#000000" stroke-width="5" transform="rotate(25 325 325)" x1="200" x2="450" y1="200" y2="450"/>
+ </g>
+ <defs>
+  <filter height="200%" id="svg_1_id_blur" width="200%" x="-50%" y="-50%">
+   <feGaussianBlur in="SourceGraphic" stdDeviation="5"/>
+  </filter>
+ </defs>
+</svg>