Debugger: support command + file launch config with program fallback and default file behavior

[Copilot]

Motivation

Debugger launch fails when workspace/file paths contain spaces because the previous default config built a single unquoted program string (for example, ruby ${file}), which gets split by the shell.
This change addresses that path-tokenization failure while preserving compatibility with existing program-based launch configs.

Implementation

• Config shape update (Option B)

  • Added first-class command + file launch configuration support.
  • Kept program as a backward-compatible fallback.

• Defaulting behavior

  • file now defaults to ${file} during config resolution when:
    • command is present
    • program is absent
    • file is omitted
  • This keeps script configs minimal while allowing explicit ${relativeFile} where needed.

• Generated debugger templates/docs

  • Debug script now emits only:

    { "type": "ruby_lsp", "name": "Debug script", "request": "launch", "command": "ruby" }

  • Debug test emits explicit relative file:

    {
      "type": "ruby_lsp",
      "name": "Debug test",
      "request": "launch",
      "command": "ruby -Itest",
      "file": "${relativeFile}"
    }

• Launch command construction hardening

  • When using command + file, the extension constructs program with quoting/escaping for the file argument.
  • Added input guards to reject newline/null-byte content in command/file before shell execution.

Automated Tests

Updated debugger unit/integration tests to:

• assert new default config output (command-first shape),
• assert file defaults to ${file} when omitted,
• exercise launch flow with a temp path containing spaces.

Manual Tests

1. Open a project in a path containing spaces.
2. Generate launch.json via “Debug: Add configuration...”.
3. Run Debug script:
   • verify config can omit file and still launches current file.
4. Run Debug test:
   • verify explicit ${relativeFile} flow still launches correctly.
5. Confirm an older config using:

   { "type": "ruby_lsp", "request": "launch", "program": "ruby ${file}" }

   still resolves through the legacy program path.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• update.code.visualstudio.com
  • Triggering command: /opt/hostedtoolcache/node/24.14.1/x64/bin/node /opt/hostedtoolcache/node/24.14.1/x64/bin/node ./out/test/runTest.js --grep Debugger (dns block)
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node node ./out/test/runTest.js --grep Debugger (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)