Allow configuration of annotation location.
I've added the ability to configure where lens annotations render relevant to the item they describe. Previously, these would render directly above the line the item is declared on. Now, there is the ability to render these annotations above the entire item (including doc comments, and attributes).
The names of the config options are up for debate, I did what seemed best to me but if anyone has better ideas let me know.
This is my first contribution so if I've missed anything please let me know.
Here's a preview of what the new option looks like:
<img width="577" alt="Screen Shot 2022-09-11 at 10 39 51 PM" src="https://user-images.githubusercontent.com/33100798/189570298-b4fcbf9c-ee49-4b79-aae6-1037ae4f26af.png">
closes https://github.com/rust-lang/rust-analyzer/issues/13218
dbb8fedf8b
