Reporter API: report files before collection

[AriPerkkio]

Clear and concise description of the problem

There is no way for a reporter to know if a file is currently being collected. If the collection phase is slow (e.g. transforms 100000 files due to barrel files), end users have no idea what is going on. Reporters cannot inform user about slow files.

Suggested solution

Before collection for a file starts, inform reporters on onTaskUpdate hook that file is in queue. It could be something like File & { mode: 'queued' }. Next expected state after this is run.

Somewhere around here:

vitest/packages/runner/src/collect.ts

Lines 31 to 35 in 0b08bc1

	const file = createFileTask(filepath, config.root, config.name, runner.pool)
	runner.onCollectStart?.(file)
	clearCollectorContext(filepath, runner)

Alternative

No response

Additional context

The summary of #6893 could display queued files even before they start running.

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.