[UI] Allow running individual tests/suites

[maxpatiiuk]

Clear and concise description of the problem

At the moment, Vitest UI allows re-running all tests in a file.
However, it is commonly useful to re-run just a single test or a suite of tests.
The option to do so is currently disabled in the UI (as this capability is not yet implemented).

Suggested solution

On however on a test/suite in the sidebar, show a button to re-run a given test/suite.
This would be similar functionality to the "Testing" panel in VS Code.

Alternative

• Run all tests in a file (slow if file has many tests)
• Stop Vitest, and re-run it with -t 'somePattern' argument passed to run only matching tests (clunky)

Additional context

Original discussion: #5948 (comment)

Validations

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