Feat: Extend code stripping to remove export syntax

[josephfh]

Summary

Extends the XState import stripping function to also strip exports so we can prevent this error showing above the code editor:

SyntaxError: export declarations may only appear at top level of a module

Also adds test coverage for both existing import and export patterns.

Verification

• pnpm test
• pnpm build
• pnpm test:e2e

Notes

• Does not strip exported types and interfaces as tsBlankSpace takes care of this
• Does not strip every possible export you might find in TS files, just common ways a user might export machines

Screenshot of the syntax error we want to avoid