Closes https://github.com/microsoft/playwright/issues/32578.
Adds a buffer mode that can be toggled by pressing <kbd>b</kbd>. When
engaged, changed test files are collected and shown on screen. The test
run is then kicked off by pressing <kbd>Enter</kbd>.
This changes the signal to start a test run from <kbd>Cmd+s</kbd> to a
<kbd>Enter</kbd> press in the test terminal. It should help users with
auto-save and make it easier to run on long-running tests. It feels very
similar to running `npx playwright test`, but without having to write a
filter.
https://github.com/user-attachments/assets/71e16139-9427-4e90-b523-8d218f09ed9d
ec2ae1ed2d