internal: KCL modules, part 1 (#4149)

Addresses #4080. (Not ready to close it yet.)

# Important

Requires a fix for #4147 before it can work in ZMA.

# Overview

```kcl
// numbers.kcl
export fn inc = (x) => {
  return x + 1
}
```

```kcl
import inc from "numbers.kcl"

answer = inc(41)
```

This also implements multiple imports with optional renaming.

```kcl
import inc, dec from "numbers.kcl"
import identity as id, length as len from "utils.kcl"
```

Note: Imported files _must_ be in the same directory.

Things for a follow-up PR:

- #4147. Currently, we cannot read files in WebAssembly, i.e. ZMA.
- Docs
- Should be an error to `import` anywhere besides the top level. Needs parser restructuring to track the context of a "function body".
- Should be an error to have `export` anywhere besides the top level. It has no effect, but we should tell people it's not valid instead of silently ignoring it.
- Error message for cycle detection is funky because the Rust side doesn't actually know the name of the first file. Message will say "b -> a -> b" instead of "a -> b -> a" when "a" is the top-level file.
- Cache imported files so that they don't need to be re-parsed and re-executed.

src/lang/queryAst.ts

@@ -28,6 +28,7 @@ import {
   getConstraintType,
 } from './std/sketchcombos'
 import { err } from 'lib/trap'
+import { ImportStatement } from 'wasm-lib/kcl/bindings/ImportStatement'
 
 /**
  * Retrieves a node from a given path within a Program node structure, optionally stopping at a specified node type.
@@ -120,7 +121,12 @@ export function getNodeFromPathCurry(
 }
 
 function moreNodePathFromSourceRange(
-  node: Expr | ExpressionStatement | VariableDeclaration | ReturnStatement,
+  node:
+    | Expr
+    | ImportStatement
+    | ExpressionStatement
+    | VariableDeclaration
+    | ReturnStatement,
   sourceRange: Selection['range'],
   previousPath: PathToNode = [['body', '']]
 ): PathToNode {