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/e2e/unit/draw.cy.js

@@ -1,7 +1,7 @@
 import 'pathseg'
 import { NS } from '../../../instrumented/svgcanvas/namespaces.js'
 import * as draw from '../../../instrumented/svgcanvas/draw.js'
-import * as units from '../../../instrumented/common/units.js'
+import * as units from '../../../instrumented/svgcanvas/units.js'
 
 describe('draw.Drawing', function () {
   const addOwnSpies = (obj) => {