This commit also excludes gitlab-shell from dependencies:

Gitaly specifies Gitlab Shell as a dependency as well in order
to use gitlabnet client to perform API endpoints to Gitlab Rails.
As a result, Gitlab Shell requires Gitaly -> Gitaly requires an
older version of Gitlab Shell -> that version requires an older
version of Gitlab Shell, etc. Let's use exclude to break the
chain earlier

After https://gitlab.com/gitlab-org/gitaly/-/merge_requests/4766
has been introduced, the test started fail because we basically
cancel the git-receive-pack after the output is received

This commit gracefully closes the connection to make the test
pass

While gitlab-shell currently has a major version of v14, the module path
it exposes is not using that major version like it is required by the Go
standard. This makes it impossible for dependents to import gitlab-shell
as a dependency without using a commit as version.

Fix this by changing the module path of gitlab-shell to instead be
`gitlab.com/gitlab-org/gitlab-shell/v14` and adjust all imports
accordingly.

Changelog: fixed

- If an integer is specified, we assume that these are seconds
- A duration of format "500ms", "10s", "1m", etc... accepted

New version of LabKit provides FIPS checks that we can use instead
of the custom code

This commit adds support of using a FIPS-validated SSL library with
compiled Go executables when `FIPS_MODE=1 make` is run. A Go compiler
that supports BoringSSL either directly (e.g. the `dev.boringcrypto`
branch) or with a dynamically linked OpenSSL
(e.g. https://github.com/golang-fips/go) is required.

This is similar to the changes to support FIPS in GitLab Runner and in
GitLab Pages:
https://gitlab.com/gitlab-org/gitlab-pages/-/merge_requests/716

Changelog: added

When gitlab-sshd has been introduced we've started running our
own SSH server. In this case we're able to cache and reuse
Gitaly connections and Registry.

It helps to reduce memory usage.