### Description

Refactors `PatternMatching` to support a map of multiple matches by key.
Based on the new `RequestKey` support for resolving.

Code Generation for `require("./dir/"+ expr)` will emit a map of
`__turbopack_lookup__({ "./a": () => ..., "./b": () => ... }, "./dir/" +
expr)`.

The output format isn't really optimized yet, that's work for future
PRs.

### Testing Instructions

added a test case, enabled one previously skipped test case



Closes PACK-2512