Expose credential methods from LibGit2 in Pkg.jl

LibGit2 offers some opportunities to Manage credentials explicitly (SSHCredential and UserPasswordCredential for example). Has there ever been made any effort to expose those to the user of Pkg.jl?
Or if not does anyone know why it was chosen to not expose those to the user?

It would be really convenient if one could do:

julia> using Pkg

julia> Pkg.add(url = "git@github.com:My_User/My_Package.jl.git", creds= my_ssh_key)

or

julia> using Pkg

julia> Pkg.add(url = "https://github.com/My_User/My_Package.jl.git", creds= my_personal_access_token)