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

src/editor/MainMenu.js

@@ -1,9 +1,8 @@
 /* globals seAlert */
-import SvgCanvas from '../svgcanvas/svgcanvas.js'
-import { convertUnit, isValidUnit } from '../common/units.js'
+import SvgCanvas from '@svgedit/svgcanvas'
 import { isChrome } from '../common/browser.js'
 
-const { $id, $click } = SvgCanvas
+const { $id, $click, convertUnit, isValidUnit } = SvgCanvas
 const homePage = 'https://github.com/SVG-Edit/svgedit'
 
 /**