Migrate vscode extension + test infrastructure to ESM

### Is your feature request related to a problem? Please describe the problem.

_No response_

### Client library/SDK language

TypeScript

### Describe the solution you'd like

Current infrastructure for vscode extension is based off commonjs as appears here https://github.com/microsoft/kiota/blob/main/vscode/microsoft-kiota/tsconfig.json#L4. We would like to experiment with moving the project to using ESM modules instead.

This was brought about as a result of a PR review as appears in this comment https://github.com/microsoft/kiota/pull/5540#discussion_r1819067720

### Additional context

_No response_

Start with vscode/microsoft-kiota/tsconfig.json and the linked PR review discussion to understand the current CommonJS setup and the requested ESM direction. Trace the VS Code extension and its test infrastructure, then verify that both use ESM consistently and that the existing tests still run successfully.

Written by the indexing model from the issue text.