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/components/ModelingSidebar/ModelingPanes/MemoryPane.test.tsx

@@ -1,6 +1,6 @@
 import { processMemory } from './MemoryPane'
 import { enginelessExecutor } from '../../../lib/testHelpers'
-import { initPromise, parse } from '../../../lang/wasm'
+import { initPromise, parse, ProgramMemory } from '../../../lang/wasm'
 
 beforeAll(async () => {
   await initPromise
@@ -29,10 +29,7 @@ describe('processMemory', () => {
     |> lineTo([2.15, 4.32], %)
     // |> rx(90, %)`
     const ast = parse(code)
-    const programMemory = await enginelessExecutor(ast, {
-      root: {},
-      return: null,
-    })
+    const programMemory = await enginelessExecutor(ast, ProgramMemory.empty())
     const output = processMemory(programMemory)
     expect(output.myVar).toEqual(5)
     expect(output.otherVar).toEqual(3)