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/useCalculateKclExpression.ts

@@ -34,6 +34,8 @@ export function useCalculateKclExpression({
 } {
   const { programMemory, code } = useKclContext()
   const { context } = useModelingContext()
+  // If there is no selection, use the end of the code
+  // so all variables are available
   const selectionRange:
     | (typeof context)['selectionRanges']['graphSelections'][number]['codeRef']['range']
     | undefined = context.selectionRanges.graphSelections[0]?.codeRef?.range
@@ -72,11 +74,12 @@ export function useCalculateKclExpression({
   }, [programMemory, newVariableName])
 
   useEffect(() => {
-    if (!programMemory || !selectionRange) return
+    if (!programMemory) return
     const varInfo = findAllPreviousVariables(
       kclManager.ast,
       kclManager.programMemory,
-      selectionRange
+      // If there is no selection, use the end of the code
+      selectionRange || [code.length, code.length]
     )
     setAvailableVarInfo(varInfo)
   }, [kclManager.ast, kclManager.programMemory, selectionRange])