Fix version bump pre-commit hook

[anirudh-bijay-glean]

What

Update the pre-commit hook for automatic version bump (.githooks/pre-commit.d/02-auto-bump-version.sh) to update plugins/glean/.codex-plugin/plugin.json and plugins/glean/.cursor-plugin/plugin.json as well.

Why

The pre-commit hook was previously updating only plugins/glean/.codex-plugin/plugin.json.

Details

The script keeps the versions across the plugin manifests in lockstep. The larger number of possible cases here makes determining the target version complex. The target version is computed as follows:

Let $V_\rm{main}$ be the set of all valid versions (across all manifests) in the main branch and $V_\rm{current}$ be the set of all valid version strings taking into consideration the staged changes. Then,

• if both $V_\rm{main}$ and $V_\rm{current}$ are empty, the script errors; else
• if $V_\rm{main} = \emptyset$, $v = \rm{max} ~ V_\rm{current}$; else
• if $V_\rm{current} = \emptyset$, $v = \rm{max}$ { $u + 0.0.1 \mid u \in V_\rm{main}$ }; else
• $v = \rm{max}$ { $\rm{max} ~ V_\rm{current}, \rm{max}$ { $u + 0.0.1 \mid u \in V_\rm{main}$ } }
  where $v$ is the target version, $\rm{max}$ is defined relative to semver comparison, and $u + 0.0.1$ increments the patch version of $u$ by 1.

Versions are assumed to be of the form $x.y.z$ (no pre-release tags/build metadata).

Missing plugin manifests do not fail the hook; however, malformed JSON in the plugin manifests does.
Missing plugin manifests and malformed JSON in the plugin manifests fail the hook.

Code changes

• Update 02-auto-bump-version.sh.
• Update the shebang of shell scripts (01-rebuild-dist.sh, 02-auto-bump-version.sh, check-version-bump.sh, pack-plugin.sh) to use the environment Bash instead of the system Bash. (start.sh has been omitted.)

[anirudh-bijay-glean]

Addressed @swarup-padhi-glean's comments. The hook now errors on missing manifests in both main and the branch after staged changes. A couple of points to note:

Deleting a manifest: When deleting a manifest, the hook's MANIFESTS list must be updated before or along with deletion of the manifest file.

Adding a manifest: The manifest must be added and the change committed and merged to main first; only after this should the hook be updated. You may alternatively bypass the hook if the change is atomic, i.e., the plugin dist does not change (so that the hook for keeping the dist up-to-date need not run).