Add `.swift-format` to the repo and format the repo with `swift-format`.
This commit does not add any automation to enforce formatting of sourcekit-lsp in CI. The goal of this commit is to get the majority of source changes out of the way so that the diff of actually enforcing formatting will have fewer changes or conflicts.
When we switch `SourceKitServer`, `SwiftLanguageServer` etc. to be actors, we can’t rely on them to provide ordering guarantees anymore because Swift concurrency doesn’t provide any ordering guarantees.
What we should thus do, is to handle all messages on a serial queue on the `Connection` level. This queue will be blocked from handling any new messages until a message has been sufficiently handled to avoid out-of-order handling of messages. For sourcekitd, this means that
a request has been sent to sourcekitd and for clangd, this means that we have forwarded the request to clangd.
Note that this serial queue is not the main thread, so we will continue accepting data over stdin, just the handling of those messages is blocked.
The asyncification changes caused some non-deterministic test failures. I believe that some of these are due to race conditions that are the result of the partial transition to actors.
Instead of merging the asyncification piece by piece, I will collect the changes asyncification changes in a branch and then qualify that branch througougly (running CI multiple times) before merging it into `main`.
When we switch `SourceKitServer`, `SwiftLanguageServer` etc. to be actors, we can’t rely on them to provide ordering guarantees anymore because Swift concurrency doesn’t provide any ordering guarantees.
What we should thus do, is to handle all messages on a serial queue on the `Connection` level. This queue will be blocked from handling any new messages until a message has been sufficiently handled to avoid out-of-order handling of messages. For sourcekitd, this means that
a request has been sent to sourcekitd and for clangd, this means that we have forwarded the request to clangd.
Note that this serial queue is not the main thread, so we will continue accepting data over stdin, just the handling of those messages is blocked.
