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.
Instead of having ad-hoc timeout durations in all the test cases, specify a default timeout duration that can be used by tests.
This allows us increase the timeout duration for all tests if we discover that e.g. sourcekitd is slower in CI setups.
rdar://91615376
We will be able to split the LSP modules off later. These LSP modules
will provide the ability to write custom LSP servers and clients in
Swift. The sourcekit-lsp repository will build on top of this new
package to provide an LSP implementation that creates a language server
for Swift and C-based-languages.
When running in debug, or in continuous integration that is not setup
for performance testing, default to not collecting performance metrics
to avoid failures due to slow or high-variability tests (default
max_stddev = 10% in xctest). Instead, run the measured block once and
skip the timing code. This has the nice side effect of speeding up test
runs in debug builds.
