fix(runner): display no projects error across all test modes

[agg23]

Alternative to #34656 that focuses on preventing the errors in the CLI, before they're encountered. Fixes #34500.

Moves parsing the project config and validating project selection to before launching UI mode. This is wasted work, but reconfiguring the config loading pipeline for test-server is a much larger change.

[github-actions]

Test results for "tests 1"

1 failed
❌ [webkit-library] › tests/library/inspector/title.spec.ts:35:5 › should update primary page URL when original primary closes @webkit-ubuntu-22.04-node18

10 flaky

⚠️ [firefox-page] › tests/page/page-evaluate.spec.ts:403:3 › should throw for too deep reference chain @firefox-ubuntu-22.04-node18
⚠️ [chromium-library] › tests/library/video.spec.ts:379:5 › screencast › should capture navigation @ubuntu-20.04-chromium-tip-of-tree
⚠️ [webkit-library] › tests/library/browsercontext-clearcookies.spec.ts:72:3 › should remove cookies by name regex @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › tests/library/capabilities.spec.ts:94:3 › should play audio @smoke @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › tests/library/selector-generator.spec.ts:591:5 › selector generator › should generate multiple: noId noText @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › tests/library/trace-viewer.spec.ts:293:1 › should show params and return value @webkit-ubuntu-22.04-node18
⚠️ [webkit-page] › tests/page/page-leaks.spec.ts:82:5 › click should not leak @webkit-ubuntu-22.04-node18
⚠️ [webkit-page] › tests/page/page-leaks.spec.ts:161:5 › waitFor should not leak @webkit-ubuntu-22.04-node18
⚠️ [webkit-page] › tests/page/page-screenshot.spec.ts:345:5 › page screenshot › should work while navigating @webkit-ubuntu-22.04-node18
⚠️ [webkit-page] › tests/page/page-set-input-files.spec.ts:205:3 › should upload multiple large files @webkit-ubuntu-22.04-node18

37839 passed, 654 skipped
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Merge workflow run.