Add "Preserve Last Action Keyword" to "Last Query Style" option in settings

[Yusyuriv]

Someone in Discord asked for this option. I think this makes perfect sense for people that often need to make a lot of different searches with the same plugin.

How it should work:

1. The plugin keyword is foo
2. User types in foo bar
3. User selects the first result, Flow Launcher hides
4. User opens Flow Launcher again
5. The search bar contains foo (with the space at the end), user can immediately begin typing new search in the same plugin