Add more functionality to the room list vm

[MidhunSureshR]

• Listen for updates from the store
• Provide a method to open rooms

[t3chguy]

Looks like insufficient coverage

[MidhunSureshR]

About the coverage, there's already tests for this in https://github.com/element-hq/element-web/pull/29368/files#diff-9d33891dc652c5aa536ce75c66f8e212abc4f4fb002f6599d518eec498e1fed6R37-R52. Will try to avoid this happening in future but would appreciate an exception this time.

[t3chguy]

I suggest copying the tests over or something as this should not land without coverage. I don't see any reason why this code needs an exception, the approach looks perfectly testable.

[florianduros]

I agree with t3chguy.
Imo, the view model should be tested independently of the view. It shouldn't rely on the view tests for its testing.

In #29368, the room list tests mock the view model. So any change to the view model is not covered by my PR's unit tests.

[MidhunSureshR]

Writing individual tests for the views and view models means testing the implementation rather than the behaviour. This is antithetical to the philosophy of RTL, see https://testing-library.com/docs/guiding-principles. We will end up with a lot of view only tests that provide little value eg: asserting that clicking a button calls the right method in the vm. We will end up with multiple tests that fail on even minor refactoring. Worse yet, testing the behaviour becomes optional since the only other way we can test the behaviour is through playwright tests and they are optional.

Anyhow, have added the tests to get this PR merged.