Test that externally-defined functions going safe -> unsafe are caught. #3009

Job	Run time
Build binary (Windows)	2m 51s
Check lint and rustfmt	47s
Semver: core-graphics	46s
Build binary	34s
Check if version changed	12s
Run tests (1.80, false)	42s
Run tests (1.81, false)	48s
Run tests (stable, false)	56s
Run tests (beta, false)	56s
Run tests (nightly, true)	56s
Semver: bevy_core v0.9.0	30s
Check failure when installed rustc is too old	15s
Caching across rustdoc versions	1m 31s
Caching with feature config changed	25s
Semver: bevy_gltf v0.9.1	55s
Semver: clap v3.2.0	38s
Semver: libp2p-dcutr 1.62.0 and libp2p-relay 0.14.0	1m 5s
Semver: libp2p-gossipsub ~0.44.0 + libp2p-request-response ~0.24.0	1m 15s
Semver: libp2p-uds 0.37.0	45s
Semver: dependency has warnings with "-Dwarnings" (libp2p v0.53.1)	1m 5s
Semver: perf-event-open-sys2 v5.0.0	16s
Semver: ref-slice fork (git)	39s
Semver: ref-slice fork (sparse)	12s
Semver: libp2p-core 0.37.0	1m 4s
Semver: sqllogictest v0.13.0	28s
Semver: tokio ~v1.25.0 (explicit)	5s
Semver: tokio ~v1.25.0 (implicit)	3s
Semver: ref-slice fork (Windows) (git)	1m 29s
Semver: ref-slice fork (Windows) (sparse)	59s
All CI stages	1s
Check for semver compliance	0s
Run the release workflow	0s
	23m 8s

Provide feedback