Correct require.context relative import keys to match Webpack (#78148)
## Add support for require.context in Turbopack
This PR adds support for `require.context` in Turbopack, allowing dynamic imports of files from a directory structure. The implementation includes:
- Fixed a bug in the `require_context.rs` file where the wrong variable was being used (`root_val` instead of `dir_val`)
- Simplified code in `RequireContextMap` implementation with pattern matching
- Added e2e tests to verify `require.context` works correctly with regex filtering
- Added a snapshot test for `require.context` functionality
- Created test files to validate the implementation against expected behavior
The PR includes a commented-out test for `require.context` without regex filtering, which will be enabled once Turbopack fully supports this feature.
Addresses: [PACK-4323](https://linear.app/vercel/issue/PACK-4323/requirecontext-behaves-differently-in-turbopack-than-in-webpack)
Fixes #78019