Feat: Shorten commit ID's in remote URL's

[AnrDaemon]

Presently, GitLens produces full commit hash on "Share remote file URL" links. It's nice and dandy, but more often than not it is unnecessary. 8 characters are more than enough to identify a commit in 99,9% repos. Even git itself uses only 7 characters in abbreviated commit names.

Self check: The gitlens.advanced.abbreviateShaOnCopy setting does not affect remote file links.

[i-vs]

likely dupe of #2160