Use go/packages instead of x/tools/loader: it allows to work
with go modules and speedups loading of packages with the help
of build cache.
A lot of linters became "fast": they are enabled by --fast now and
work in 1-2 seconds. Only unparam, interfacer and megacheck
are "slow" linters now.
Average project is analyzed 20-40% faster than before if all linters are
enabled! If we enable all linters except unparam, interfacer and
megacheck analysis is 10-20x faster!
A recent change was introduced in goimports improving how it sort and
format imports in https://go-review.googlesource.com/c/tools/+/116795
This commit updates the vendored version of the golang.org/x/tools
repository to include these changes.
