Rollup merge of #148073 - epage:org-frontmatter, r=jieyouxu

test(frontmatter): Rename tests to make coverage more obvious

When working on the stabilization report (rust-lang/rust#148051), I found it annoying to determine what cases were covered because areas of the frontmatter feature were either not in the file name or in inconsistent locations.

This moves the area of frontmatter to the start of the file name and the moves to more specific the later in the file name so coverage is easier to see.

Tracking issue: rust-lang/rust#136889

Author: jhpratt