Add lexical scope and redefining variables in functions (#3015)

* Fix to allow variable shadowing inside functions

* Implement closures

* Fix KCL test code to not reference future tag definition

* Remove tag declarator from function parameters

This is an example where the scoping change revealed a subtle issue
with TagDeclarators.  You cannot bind a new tag using a function
parameter.

The issue is that evaluating a TagDeclarator like $foo binds an
identifier to its corresponding TagIdentifier, but returns the
TagDeclarator.  If you have a TagDeclarator passed in as a parameter
to a function, you can never get its corresponding TagIdentifier.

This seems like a case where TagDeclarator evaluation needs to be
revisited, especially now that we have scoped tags.

* Fix to query return, functions, and tag declarator AST nodes correctly

src/lang/std/sketchcombos.ts

@@ -1636,8 +1636,8 @@ export function transformAstSketchLines({
     })
 
     const varName = varDec.node.id.name
-    let sketchGroup = programMemory.root?.[varName]
-    if (sketchGroup.type === 'ExtrudeGroup') {
+    let sketchGroup = programMemory.get(varName)
+    if (sketchGroup?.type === 'ExtrudeGroup') {
       sketchGroup = sketchGroup.sketchGroup
     }
     if (!sketchGroup || sketchGroup.type !== 'SketchGroup')