Migrate some more integration tests

[jesseduffield]

• PR Description

I migrated some more integration tests while on the plane to the states. Here they are!

Some important notes:

• integration tests now run in parallel. It's possible that this can cause flakiness, because all tests wait 100ms before pressing their first key to allow views to refresh, and if a goroutine is stopped and then resumed, the 100ms could elapse without the views having even started refreshing.
• the virtual screen is 100x100 characters, which should be big enough for most things. The helper function that lets you move your cursor to a particular line depends on that line already being visible in the view, meaning flakiness occurs if the screen is too small and the item is outside the visible content.
• there were some rebase-related test failures. I'm pretty sure this was caused by the fact that if you try to press 'd' on a commit and you're in rebase mode but the commit hasn't been refreshed to consider itself as being a rebasing commit, you get asked whether you want to delete the commit (implicitly starting a rebase session). Ideally we should just have a way of asserting that we're done refreshing anything, but that'll take more work.

• Please check if the PR fulfills these requirements

• Cheatsheets are up-to-date (run go run scripts/cheatsheet/main.go generate)
• Code has been formatted (see here)
• Tests have been added/updated (see here for the integration test guide)
• Text is internationalised (see here)
• Docs (specifically docs/Config.md) have been updated if necessary
• You've read through your own file changes for silly mistakes etc