Add `coverage` scope for controlling paths in code coverage This PR adds a `coverage` scope (for `-Zremap-path-scope`) for controlling if the paths that ends up in code coverage output should be remapped or not. Currently code coverage use the `macro` scope which is not a appropriate scope for them. Found during the stabilization of `-Zremap-path-scope` https://github.com/rust-lang/rust/pull/147611#issuecomment-3396210043 and was asked to be in a separate PR in https://github.com/rust-lang/rust/pull/147611#issuecomment-3448455252. r? compiler
The codegen crate contains the code to convert from MIR into LLVM IR,
and then from LLVM IR into machine code. In general it contains code
that runs towards the end of the compilation process.
For more information about how codegen works, see the rustc dev guide.