MV3 e2e Testcases

[hilvmason]

For continue the MV3-specific e2e work, this epic represents a collection of relevant scenarios.

It would be great to have some eyes on it, in case I (@seaona) am missing something.

Specially if you have been contributing directly with MV3 PRs, think on how your PR could potentially fail and if having an e2e test would help you to have a better sleep. Also, bear in mind that the capacity is limited, so this would be done gradually - that's why is important to prioritise the most important scenarios first.