Fix standard query lockfile detection

[Pybsama]

Summary

• detect existing standard-query pack lockfiles from the real filesystem instead of codeql pack packlist output
• support both qlpack.lock.yml and codeql-pack.lock.yml
• preserve the existing temporary dependency-install and cleanup flow when no lockfile exists

Tests

• npm run test:vscode-integration:no-workspace -- --runTestsByPath test/vscode-tests/no-workspace/local-queries/standard-queries.test.ts
• npm run test:vscode-integration:no-workspace
• npm run build
• npm run lint
• npm run check-types
• npm run lint:markdown

Fixes #4471