Add server-side input validation for repo insertions

[patrickdevivo]

Related to this work: https://github.com/mergestat/fuse/pull/157 we should add server-side input validation and normalization when adding a new repo, to enforce things like https prefix

[codecov-commenter]

Codecov Report

Merging #162 (a398f73) into main (43799f5) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #162   +/-   ##
=======================================
  Coverage   68.34%   68.34%           
=======================================
  Files          36       36           
  Lines        1744     1744           
=======================================
  Hits         1192     1192           
  Misses        355      355           
  Partials      197      197           

Impacted Files	Coverage Δ
extensions/internal/git/native/blame.go	64.36% <ø> (ø)
extensions/internal/git/native/files.go	63.33% <ø> (ø)
extensions/internal/git/native/stats.go	61.73% <ø> (ø)
extensions/internal/github/org_repos.go	75.34% <ø> (ø)
extensions/internal/github/repo_issues.go	71.22% <ø> (ø)
extensions/internal/github/repo_prs.go	75.14% <ø> (ø)
extensions/internal/github/stargazers.go	71.56% <ø> (ø)
extensions/internal/github/starred_repos.go	68.88% <ø> (ø)
extensions/internal/github/user_repos.go	72.60% <ø> (ø)

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[patrickdevivo]

Something to consider here is also repo normalization - for instance https://github.com/mergestat/mergestat vs https://github.com/mergestat/mergestat/.

Both are considered separate repos right now, when they should be recognized as the same