feat: line polygons (#9477)

* Loop Lock/Unlock

* fixed condition. 4 line points are required for the action to be available

* extracted updateLoopLock to improve readability. Removed unnecessary SVG attributes

* lint + added loopLock to restore.ts

* added  loopLock to newElement, updated test snapshots

* lint

* dislocate enpoint when breaking the loop.

* change icon & turn into a state style button

* POC: auto-transform to polygon on bg set

* keep polygon icon constant

* do not split points on de-polygonizing & highlight overlapping points

* rewrite color picker to support no (mixed) colors & fix focus handling

* refactor

* tweak point rendering inside line editor

* do not disable polygon when creating new points via alt

* auto-enable polygon when aligning start/end points

* TBD: remove bg color when disabling polygon

* TBD: only show polygon button for enabled polygons

* fix polygon behavior when adding/removing/moving points within line editor

* convert to polygon when creating line

* labels tweak

* add to command palette

* loopLock -> polygon

* restore `polygon` state on type conversions

* update snapshots

* naming

* break polygon on restore/finalize if invalid & prevent creation

* snapshots

* fix: merge issue and forgotten debug

* snaps

* do not merge points for 3-point lines

---------

Co-authored-by: dwelle <5153846+dwelle@users.noreply.github.com>

packages/excalidraw/locales/en.json

@@ -141,6 +141,10 @@
       "edit": "Edit line",
       "editArrow": "Edit arrow"
     },
+    "polygon": {
+      "breakPolygon": "Break polygon",
+      "convertToPolygon": "Convert to polygon"
+    },
     "elementLock": {
       "lock": "Lock",
       "unlock": "Unlock",