branches: support require linear history

[marcoieni]

Very similar to #2374. Just a different option.

GitHub GraphQL docs.

[github-actions]

Dry-run check results

[WARN  rust_team::sync] sync-team is running in dry mode, no changes will be applied.
[INFO  rust_team::sync] synchronizing crates-io
[INFO  rust_team::sync] synchronizing github

[marcoieni]

Branch settings edited in this PR:

• https://github.com/rust-lang/docs.rs/settings/branch_protection_rules/70108634
• https://github.com/rust-lang/infra-smoke-tests/settings/branch_protection_rules/48096338
• https://github.com/rust-lang/odht/settings/branch_protection_rules/19884231
• https://github.com/rust-lang/thorin/settings/branch_protection_rules/23222430

[marcoieni]

[rustbot]

rust_team_data/src/v1.rs has been modified, it is used (as a git dependency) by multiple sub-projects like triagebot, the www.rust-lang.org website and others.

If you are changing the data structures, please make sure that the changes are not going to break serde deserialization (adding a field is fine; removing or renaming a field isn't).

If you must do a breaking change to the format, make sure to coordinate it with all the users of the rust_team_data crate.