Rather than eagerly converting JSON, we losslessly keep it as is, and
change the shape of user-submitted data at the last moment.
This also allows us to remove a bunch of wrong Defaults
I found that `textDocument/formatting` was always returning a full
`TextEdit` replacement, even when there are no changes, which caused Vim
(w/ vim-lsp) to always indicate a modified buffer after formatting. We
can easily compare whether there were changes and return `null` if not,
so the client knows there's nothing to do.
The idea here is that, on CI, we only want to cache crates.io
dependencies, and not local crates. This keeps the size of the cache
low, and also improves performance, as network and moving files on
disk (on Windows) can be slow.
