Add script to add overlay annotations

[kaspersv]

This PR adds a script to automatically add sensible default annotations to files without existing overlay annotations. The script uses naming heuristics to determine which files to annotate. The script adds a module-level overlay[local?] annotation and annotates all non-private inline predicates overlay[caller] for selected files. Maintenance of overlay annotations in already annotated files is not the responsibility of this script and will be handled using QL-for-QL queries. This is intended to allow QL authors to gradually take ownership of overlay annotations and manually add & remove automatically added overlay annotations.

A CI check will be added in a subsequent PR to check that the script has been run for select languages.

The script is based on @ginsbach's annotation script. However, instead of removing existing overlay annotations, it only annotates files without existing annotations and offloads maintenance of annotated files to QL-for-QL queries.

For https://github.com/github/codeql-core/issues/4951.

[Copilot]

Pull Request Overview

Adds a new Python script to automatically insert default overlay annotations into .qll files that lack them, based on naming and content heuristics.

• Implements add-overlay-annotations.py to add module-level overlay[local?] and inline overlay[caller] annotations.
• Skips files with existing annotations, tests, dataflow configs, or empty content.
• Targets specified languages under <lang>/ql/lib and a shared directory.

Comments suppressed due to low confidence (1)

config/add-overlay-annotations.py:106

• New annotation logic isn't covered by any tests; consider adding unit tests for annotate_as_appropriate, insert_overlay_caller_annotations, and the top-level function to prevent regressions.

def annotate_as_appropriate(filename, lines):