They don't need ASTs or anything, so they should still run immediately.
These were sync for historical reasons (they predate clangd having a pervasive
threading model). This worked ok as they were "cheap".
Aside for consistency, there are a couple of reasons to make them async:
- they do IO (finding .clang-format) so aren't trivially cheap
- having TUScheduler involved in running these tasks means we can use it as an injection point for configuration. (TUScheduler::run will need to learn about which file is being operated on, but that's an easy change).
- adding the config system adds more potential IO, too