Merge find functionalities

[Zisu Andrei]

As discussed on slack, we have two different ways of searching in Files:
* direct typing, which only looks in the same folder
* ctrl+f, which performs a nested search.

This is confusing and non-obvious.

Dan's suggestion is "They should do the same thing, and the pwd (basically type-ahead) should always be preferred as the top result".

[Jeremy Wootten (jeremywootten)]

We need to make sure that this does not slow down the current folder search noticeably and that the "begins with" results come first so that you can still use this functionality as a quick way of navigating (type first few letters of folder then enter)