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__/scenario4-check tool_fhrect.svg

@@ -0,0 +1,7 @@
+<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>
+  <rect fill="#FF0000" height="50" id="svg_1" stroke="#000000" width="100" x="150" y="150"/>
+  <rect fill="#FF0000" height="100" id="svg_2" stroke="#000000" width="120" x="350" y="230"/>
+ </g>
+</svg>