For the "cli" and "tui" modes of the test runner there's a "-race" parameter to
turn it on; for running tests on CI with go test, you turn it on by setting the
environment variable LAZYGIT_RACE_DETECTOR to a non-empty value.
We've been sometimes using lo and sometimes using my slices package, and we need to pick one
for consistency. Lo is more extensive and better maintained so we're going with that.
My slices package was a superset of go's own slices package so in some places I've just used
the official one (the methods were just wrappers anyway).
I've also moved the remaining methods into the utils package.
