fix(test): resolve tsconfig extends via Node resolution

[pravinireri]

Summary

Resolves bare specifiers in tsconfig.json extends using Node module resolution.

Why

Playwright 1.62 started failing loudly when a tsconfig extends path cannot be resolved. That exposed a regression where Playwright could not resolve package-based tsconfig extends that TypeScript resolves successfully.

This affected cases such as:

• hoisted config packages, for example foo/tsconfig.json
• package exports subpaths, for example @repo/tsconfig/next
• root package exports, for example typescript-config-silverwind

Change

Falls back to Node resolution for bare extends specifiers when the existing relative and immediate node_modules probes do not resolve the config.

Relative and absolute extends behavior is unchanged, and genuinely unresolvable extends paths still fail loudly.

Tests

• npm run ttest -- resolver.spec.ts --grep "extends"

Fixes #41989

[Copilot]

Pull request overview

This PR fixes Playwright’s tsconfig loader to resolve bare extends specifiers using Node-style module resolution (matching tsc behavior), addressing a 1.62 regression where previously-unresolved package-based extends paths now fail loudly.

Changes:

• Add a fallback in resolveConfigFile() to require.resolve() bare extends specifiers (walk-up node_modules, honoring package.json exports/main) before throwing.
• Add resolver tests covering hoisted config packages, exports subpaths, root export resolution, and the still-failing unresolvable bare specifier case.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
packages/playwright/src/transform/tsconfig-loader.ts	Adds Node module-resolution fallback for bare extends specifiers when existing probes fail.
tests/playwright-test/resolver.spec.ts	Adds regression tests for hoisted packages and package.json exports-based tsconfig resolution.