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/modifyAst.ts

@@ -983,7 +983,7 @@ export async function deleteFromSelection(
           if (err(parent)) {
             return
           }
-          const sketchToPreserve = programMemory.root[sketchName] as SketchGroup
+          const sketchToPreserve = programMemory.get(sketchName) as SketchGroup
           console.log('sketchName', sketchName)
           // Can't kick off multiple requests at once as getFaceDetails
           // is three engine calls in one and they conflict