A remote such as `gh:owner/repo`, where `gh` is an `~/.ssh/config` alias
for github.com, keyed as `gh/owner/repo`, so the same repository cloned
with and without the alias showed up as two projects.

Resolve SSH remotes through `ssh -G` (with the remote's user and port, so
`Match` rules apply) and key them by the HostName it reports. Git keeps
using the raw remote. On plain servers a relative path is keyed under its
login's home (`~user/path`), so two logins on one host stay two
repositories. `normalizeGitRemoteUrl` now reads SCP remotes without a
user and with an absolute path.

Covers the remaining edge cases found in review:

- public forge hosts and their port-443 endpoints skip ssh
- a loopback HostName keeps the alias but still keys the login's home
- a config User git cannot spell in a remote is ignored
- one-letter hosts with a user stay SSH remotes; without one they are drives
- git+ssh:// and ssh+git:// key like ssh://

…motes

# Conflicts:
#	apps/server/src/project/RepositoryIdentityResolver.ts
#	packages/shared/src/git.ts