Add LGitRemote>>defaultBranchName (again)

[tinchodias]

No description provided.

[tinchodias]

More info here: #40

[tinchodias]

I recovered the manual test's mechanism to load credentials and personal repo's urls. It worked on my computer like this:

1. On image's directory, create a file name test_data.json.
2. Fill with your information:

{
  "urls" : {
    "repositoryUrlHttps" : "https://github.com/tinc...ias/libgit2-pharo-bindings.git",
    "repositoryUrlSsh" : "git@github.com:tinc...dias/libgit2-pharo-bindings.git"
  },
  "credentials" : {
    "username" : "tinc...ias",
    "password" : "a5...2e"
  }
}

where password had my personal token, the one I use to push to GH
and "tin...dias" is my user (not so secret as the token but :p...)

3. Run LGitManualFetchTest >> testDefaultBranchName

[tinchodias]

This MCFileTreeJsonParser doesn't exist in P11

[tinchodias]

@guillep I don't remember why I added this. My Pharo 14 with vmLatest has LGitLibrary uniqueInstance version "#(1 9 0)", I guess I can remove this change

[guillep]

Just tell me when this is mergeable :)