chore: Rust checks are required + merge queue (#21941)

Closes #6880
Follow up on #17538 and
#21239

#21239 seems to be working fine
- time to make all the rust changes required to merge it.

This brings two cool things:

1. The most important one - the "merge when ready" button now works 🚀
<img width="923" height="285" alt="image"
src="https://github.com/user-attachments/assets/4f11ecb6-e1d9-473f-815f-b57488042dd3"
/>

You can click this button any time, even right after opening a PR. It
will be automatically merged when:
- all required CI checks (which now include rust) are passing
- you get an approval

I think this should help quite a bit. A lot of people get an approval,
push a nit, and then sit waiting for CI to finish. No more waiting!!

2. We protect ourselves from logical conflicts: cases where develop was
passing before, but someone merged something in the meantime and now
your change is broken on develop - and you don't find out until after
you merge. We hit this almost every month.

One downside: before, clicking merge would happen instantly (although
you had **manually** to wait for tests to be green). With this PR, you
won't have to wait, but it will take 16 minutes to merge (plus, 16 more
to put in the merge queue if you just pushed). But github will do the
work itself and ensure tests are passing on the latest `main`.

Author: blaginin

.asf.yaml

@@ -60,6 +60,29 @@ github:
           - "Spell Check with Typos"
           - "Circular Dependency Check"
           - "Detect Unused Dependencies"
+          - "linux build test"
+          - "cargo check datafusion-common features"
+          - "cargo check datafusion-substrait features"
+          - "cargo check datafusion-proto features"
+          - "cargo check datafusion features"
+          - "cargo check datafusion-functions features"
+          - "cargo test (amd64)"
+          - "cargo test datafusion-cli (amd64)"
+          - "cargo examples (amd64)"
+          - "cargo test doc (amd64)"
+          - "cargo doc"
+          - "build and run with wasm-pack"
+          - "verify benchmark results (amd64)"
+          - "Run sqllogictest with Postgres runner"
+          - "Run sqllogictest in Substrait round-trip mode"
+          - "cargo test (macos-aarch64)"
+          - "Verify Vendored Code"
+          - "Check cargo fmt"
+          - "clippy"
+          - "check Cargo.toml formatting"
+          - "check configs.md and ***_functions.md is up-to-date"
+          - "check example README is up-to-date"
+          - "Verify MSRV (Min Supported Rust Version)"
     # needs to be updated as part of the release process
     # .asf.yaml doesn't support wildcard branch protection rules, only exact branch names
     # https://github.com/apache/infrastructure-asfyaml?tab=readme-ov-file#branch-protection

.github/workflows/rust.yml

@@ -33,14 +33,11 @@ on:
       - ".github/ISSUE_TEMPLATE/**"
       - ".github/pull_request_template.md"
   pull_request:
-    paths-ignore:
-      - "docs/**"
-      - "**.md"
-      - ".github/ISSUE_TEMPLATE/**"
-      - ".github/pull_request_template.md"
   # manual trigger
   # https://docs.github.com/en/actions/managing-workflow-runs/manually-running-a-workflow
   workflow_dispatch:
+  merge_group:
+
 
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   contents: read