editor: initialize `.vscode` settings directory #13385

Job	Run time
Check protos	24s
build (ubuntu-latest)	4m 30s
Build jj-lib without Git support	45s
build (macos-13)	9m 16s
Check formatting	15s
build (macos-14)	3m 39s
build (windows-latest)	9m 36s
cargo-deny (advisories)	25s
build (ubuntu-latest, --all-features)	5m 23s
cargo-deny (bans licenses sources)	23s
Clippy check	2m 34s
Check that MkDocs can build the docs	23s
Check that MkDocs can build the docs with Poetry 1.8	20s
	37m 53s

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