Run the per-language bundle check on its feature branch

Per-language bundles are not yet published as part of a release, so this
check points at a pre-release and needs exercising before it can run on
`main`. Allow a check to opt in to running on additional branches so that
it can be, without opening a pull request.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: d4c7b873-8278-4a36-b67c-6cc5ea3b2316

.github/workflows/__per-language-bundle.yml

@@ -12,6 +12,7 @@ on:
     branches:
       - main
       - releases/v*
+      - henrymercer/per-language-bundles
   pull_request: {}
   merge_group:
     types:

pr-checks/checks/per-language-bundle.yml

@@ -2,6 +2,10 @@ name: "Per-language bundle"
 description: "Tests that a CodeQL bundle containing only a single language can analyze that language"
 versions:
   - linked # Unused: this test pins `tools` to a specific per-language bundle.
+# TODO: Remove once per-language bundles ship in a release, so that this check no longer needs to be
+# exercised on a feature branch.
+extraPushBranches:
+  - henrymercer/per-language-bundles
 steps:
   - id: init
     uses: ./../action/init

pr-checks/sync.ts

@@ -90,6 +90,13 @@ interface Specification extends JobSpecification {
 
   /** If set, this check is part of a named collection that gets its own caller workflow. */
   collection?: string;
+
+  /**
+   * Additional branches on which a push should run this check.
+   *
+   * Useful for temporarily exercising a check on a feature branch without opening a pull request.
+   */
+  extraPushBranches?: string[];
 }
 
 /** Minimal type to represent steps in Actions workflows. */
@@ -763,7 +770,11 @@ function main(): void {
       },
       on: {
         push: {
-          branches: ["main", "releases/v*"],
+          branches: [
+            "main",
+            "releases/v*",
+            ...(checkSpecification.extraPushBranches ?? []),
+          ],
         },
         pull_request: {},
         merge_group: {