Add --service flag, output modes (--quiet/--json/--silent), and deprecate --buildtypeid

[katbyte]

Adds service-level targeting, output verbosity controls, and several quality-of-life improvements.

New Features

--service flag

• Target specific services when triggering builds: --service network,compute
• Use --service all to target every service
• Validates service names against the GitHub repo via the Contents API
• Without --all, filters discovered tests to the specified services
• With --all, bypasses test discovery and runs TestAcc for each service directly

Output modes (cout package)

• --quiet — minimal machine-readable output: PR@SERVICE@BUILDID URL (one line per build)
• --json — JSON array of all triggered builds, output at the end
• --silent — suppress all output (errors still print to stderr)
• All modes configurable via environment variables (TCTEST_OUTPUT_QUIET, TCTEST_OUTPUT_JSON, TCTEST_OUTPUT_SILENT)
• New lib/cout package centralises output control using gookit/color, preserving colour tags while respecting verbosity levels

--build-link-force-old-ui

• Appends &fromSakuraUI=true to build URLs to force the classic TeamCity UI

--build-type-id (replaces --buildtypeid)

• New --build-type-id flag uses the build type ID as-is (no _SERVICE suffix appended)
• Opt-in to old behaviour with --build-type-id-add-service-suffix
• --buildtypeid/-b still works but prints a deprecation warning and enables service suffix automatically
• Errors if both --buildtypeid and --build-type-id are used simultaneously

Other Changes

• Added environment variables for --comment (TCTEST_COMMENT), --build-link-force-old-ui (TCTEST_FORCE_OLD_UI)
• Comprehensive README update covering all new flags, output modes with examples, and environment variables

[mstroob]

LGTM