tests: add additional coverage for metaedit and describe #6807

Job	Run time
build (no git)	1m 38s
nix flake (macos-14)	13m 29s
nix flake (ubuntu-24.04-arm)	6m 54s
nix flake (ubuntu-24.04)	7m 37s
test (macos-x86_64)	5m 39s
test (linux-aarch64-gnu)	6m 8s
test (linux-x86_64-gnu)	6m 8s
test (macos-aarch64)	6m 5s
test (windows-aarch64)	16m 9s
test (windows-x86_64)	16m 12s
check (latest mkdocs, optional)	7m 27s
check (rustfmt)	19s
check (zizmor)	22s
check (Cargo.lock dependency count)	5s
check (protos)	2m 3s
check (clippy)	1m 28s
check (cargo-deny, advisories)	30s
check (cargo-deny, bans)	28s
check (mkdocs)	19s
check (cargo-deny, sources)	25s
check (codespell)	14s
check (cargo-deny, licenses)	31s
check (doctests)	3m 11s
required checks (merge queue)	-1s
	1h 43m 20s

Provide feedback