Add Debian packaging and vendored deps

.gitlab-ci.yml

debian/changelog

debian/compat

debian/control

debian/copyright

debian/rules

debian/source/format

vendor/github.com/beorn7/perks/LICENSE

vendor/github.com/beorn7/perks/quantile/exampledata.txt

vendor/github.com/beorn7/perks/quantile/stream.go

vendor/github.com/cespare/xxhash/v2/.travis.yml

vendor/github.com/cespare/xxhash/v2/LICENSE.txt

vendor/github.com/cespare/xxhash/v2/README.md

vendor/github.com/cespare/xxhash/v2/go.mod

vendor/github.com/cespare/xxhash/v2/go.sum

vendor/github.com/cespare/xxhash/v2/xxhash.go

vendor/github.com/cespare/xxhash/v2/xxhash_amd64.go

vendor/github.com/cespare/xxhash/v2/xxhash_amd64.s

vendor/github.com/cespare/xxhash/v2/xxhash_other.go

vendor/github.com/cespare/xxhash/v2/xxhash_safe.go