Migrate to fluxcd/pkg

cmd/tk/bootstrap_github.go

cmd/tk/bootstrap_gitlab.go

cmd/tk/create_source_git.go

go.mod

go.sum

pkg/git/provider.go

pkg/git/provider_github.go

pkg/git/provider_gitlab.go

pkg/git/repository.go

pkg/ssh/host_key.go

pkg/ssh/key_pair.go

pkg/ssh/knownhosts/LICENSE

pkg/ssh/knownhosts/knownhosts.go

pkg/ssh/knownhosts/knownhosts_test.go