Add offset plane point-and-click user flow (#4552)

* Add a code mod for offset plane

* Add support for default plane selections to our `otherSelections` object

* Make availableVars work without a selection range
(because default planes don't have one)

* Make default planes selectable in cmdbar even if AST is empty

* Add offset plane command and activate in toolbar

* Avoid unnecessary error when sketching on offset plane by returning early

* Add supporting test features for offset plane E2E test

* Add WIP E2E test for offset plane
Struggling to get local electron test suite running properly

* Typos

* Lints

* Fix test by making it a web-based one:
I couldn't use the cmdBar fixture with an electron test for some reason.

* Update src/lib/commandBarConfigs/modelingCommandConfig.ts

* Update src/machines/modelingMachine.ts

* Revert changes to `homePageFixture`, as they were unused

* @Irev-Dev feedback: convert action to actor, fix machine layout

* Update plane icon to be not dashed, follow conventions closer

src/lib/constants.ts

@@ -54,6 +54,7 @@ export const KCL_DEFAULT_CONSTANT_PREFIXES = {
   EXTRUDE: 'extrude',
   SEGMENT: 'seg',
   REVOLVE: 'revolve',
+  PLANE: 'plane',
 } as const
 /** The default KCL length expression */
 export const KCL_DEFAULT_LENGTH = `5`