FR: search file by name in all repositories

Problem to solve

Allow user to find file(s) in Git repositories, when user knows name of target file, but doesn't know in which repositories to look for it.

E.g.:

• find all robots.txt in all repos
• find all *.exe in all repos

Proposal

Implement a search by filename in Git repositories that are available to the user for reading. User should be able to search by exact filename match or using fileglob patterns.