fix: ensure generated tsconfig paths start with ./ if aliasing to ./svelte-kit

[teemingc]

fixes #12169

Appends a "./" to the generated tsconfig path so that aliases to files in .svelte-kit/... don't cause the user's tsconfig.json to complain about non-relative paths.

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[benmccann]

actually, maybe it'd be more accurate or comprehensive to say:

Suggested change

	fix: correctly handle aliases to files in the `.svelte-kit` directory
	fix: correctly handle aliases to files in hidden directories

[teemingc]

I'm not sure that's right. The only issue was that aliases to files in .svelte-kit did not start with a leading ./ so tsconfig considered them to be non-relative paths and complained e.g. "types/routes/src/*"