Rollup merge of #148139 - Urgau:add-coverage-scope, r=Zalathar

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` rust-lang/rust#147611 (comment) and was asked to be in a separate PR in rust-lang/rust#147611 (comment).

r? compiler

Author: Zalathar