Persist CodeQL version output to file rather than environment

[mario-campos]

Currently, the output of codeql version is cached and persisted between steps as an environment variable. This is fine, for now, but, as we begin to cache more of the CLI, we should persist that output to a file instead because:

1. There is a limit to the size of a process' environment. On GitHub Actions, the runners already have a populated environment. And, the output of these CLI commands may be verbose.
2. There is data to suggest that a larger environment has performance implications (more environment variables -> more memory for the kernel to copy during execve(2)).

To that end, and as a precaution, this PR replaces $CODEQL_ACTION_CLI_VERSION_INFO with $CODEQL_ACTION_TEMP/version.json, a file-backed cache for codeql version.

Changes

• Moved the CodeQL CLI version caching logic from util.ts (which used environment variables) into a new module src/cli/output-cache.ts, which now uses a temporary on-disk file (codeql-action-command-cache.json) for cross-step persistence. This includes new functions for caching, retrieving, and resetting the cached version, as well as improved validation of persisted data.
• Moved the VersionInfo type definition from codeql.ts to a new shared file src/cli/types.ts, and updated all references to use the new location. This centralizes type definitions to avoid cyclic dependencies.
• Removed the now-obsolete CODEQL_VERSION_INFO environment variable from EnvVar in environment.ts.

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Risk assessment

For internal use only. Please select the risk level of this change:

• Low risk: Changes are fully under feature flags, or have been fully tested and validated in pre-production environments and are highly observable, or are documentation or test only.

Which use cases does this change impact?

Workflow types:

• Advanced setup - Impacts users who have custom CodeQL workflows.
• Managed - Impacts users with dynamic workflows (Default Setup, Code Quality, ...).

Products:

• Code Scanning - The changes impact analyses when analysis-kinds: code-scanning.
• Code Quality - The changes impact analyses when analysis-kinds: code-quality.

Environments:

• Dotcom - Impacts CodeQL workflows on github.com and/or GitHub Enterprise Cloud with Data Residency.
• GHES - Impacts CodeQL workflows on GitHub Enterprise Server.

How did/will you validate this change?

• Unit tests - I am depending on unit test coverage (i.e. tests in .test.ts files).
• End-to-end tests - I am depending on PR checks (i.e. tests in pr-checks).

If something goes wrong after this change is released, what are the mitigation and rollback strategies?

• Rollback - Change can only be disabled by rolling back the release or releasing a new version with a fix.

How will you know if something goes wrong after this change is released?

• Telemetry - I rely on existing telemetry or have made changes to the telemetry.
  • Alerts - New or existing monitors will trip if something goes wrong with this change.

Are there any special considerations for merging or releasing this change?

• No special considerations - This change can be merged at any time.

Merge / deployment checklist

• Confirm this change is backwards compatible with existing workflows.
• Consider adding a changelog entry for this change.
• Confirm the readme and docs have been updated if necessary.

[Copilot]

Pull request overview

Moves persisted CodeQL CLI version metadata from an environment variable to a temporary JSON file.

Changes:

• Writes and reads version metadata from $CODEQL_ACTION_TEMP/version.json.
• Removes the obsolete environment variable.
• Updates persistence tests.

Show a summary per file

File	Description
src/util.ts	Implements file-based version caching.
src/util.test.ts	Updates cache-reading tests.
src/environment.ts	Removes the old cache environment variable.

Review details

• Files reviewed: 3/3 changed files
• Comments generated: 1
• Review effort level: Balanced

[mbg]

Thanks for picking this back up! I have added a few inline (mostly style) comments.

Some high-level points:

• Also added as an in-line comment, but do you plan to have a separate file for each command? If so, why? On the same topic, if not, then should the file be more structured to allow for relevant metadata and other command output down the line?
• Have you had any more thoughts about either checking that the cached file is intended for the current analysis (e.g. by checking the generated jobUuid) or deleting cache files on "startup"?
• Add a unit test for the case where the file cannot be read (e.g. because it doesn't exist).
• The linter CI is failing. Remember to run npm lint locally before committing / pushing changes.

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Much more minor, but I spotted this in the PR description:

This is fine, for now, but, as we begin to cache more of the CLI, we should persist that output to a file instead.

The reasoning here ("as we begin to cache more of the CLI") doesn't really justify the conclusion ("we should persist that output to a file instead). Could you edit that to actually highlight why files are preferable to environment variables?

[mbg]

LGTM, aside from addressing the minor point about the logging the error and resolving the merge conflict.