templater: add special "self" variable to refer to top-level object #9390

Job	Run time
build (ubuntu-latest)	3m 3s
build (ubuntu-latest)	3m 3s
build (macos-14)	2m 32s
build (macos-14)	2m 32s
cargo-deny (advisories)	29s
cargo-deny (advisories)	29s
build (windows-latest)	15m 1s
build (windows-latest)	7m 16s
cargo-deny (bans licenses sources)	25s
cargo-deny (bans licenses sources)	25s
build (ubuntu-latest, --all-features)	4m 12s
build (ubuntu-latest, --all-features)	4m 12s
Check that MkDocs can build the docs	24s
Check that MkDocs can build the docs	24s
Check that MkDocs can build the docs with Poetry 1.3.2	34s
Check that MkDocs can build the docs with Poetry 1.3.2	34s
Check formatting	16s
Check formatting	16s
Clippy check	2m 14s
Clippy check	2m 14s
Check protos	24s
Check protos	24s
	51m 23s

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