[New Requirement] gitlab plugin(GitLab Files) support only fetch one file

[huangoliver]

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Current gitlab files can get all files under path, if the files is huge in path, it will slow down the node, if i do know which file I want to fetch, I think we can support only fetch one file.

[huangoliver]

From the ReadME: A tool for query GitLab files, Input should be branch and a exists file or directory path. It show that supoort a exists file, but from source code, it doesn't support.