8021: Enable searching for builtin types r=matklad a=Veykril
Not too sure how useful this is for reference search overall, but for completeness sake it should be there
![image](https://user-images.githubusercontent.com/3757771/111132711-f69db600-8579-11eb-8c90-22fd6862d11f.png)
Also enables document highlighting for them.
8022: some clippy::performance fixes r=matklad a=matthiaskrgr
use vec![] instead of Vec::new() + push()
avoid redundant clones
use chars instead of &str for single char patterns in ends_with() and starts_with()
allocate some Vecs with capacity to avoid unnecessary resizing
Co-authored-by: Lukas Wirth <lukastw97@gmail.com>
Co-authored-by: Matthias Krüger <matthias.krueger@famsik.de>