[clang][modules][deps] Preserve module map load order

[clang][modules][deps] Preserve module map load order

In `ASTWriter`, input files are sorted based on whether they are system or user. The current implementation used single `std::queue` with `push_back` and `push_front`. This resulted in the user files being reversed.

This patch fixes that by keeping the system/user distinction, but otherwise serializing files in the order they were loaded by the `SourceManager`. This is then used in the dependency scanner to report module map dependencies in the correct order.

Depends on D134224.

Reviewed By: Bigcheese

Differential Revision: https://reviews.llvm.org/D134248