fix(mr.create): consider remote branches

[levouh]

Fix #296

[levouh]

Converting to draft to test first, will move back when testing is done.

[levouh]

Not sure if it is worth adding a require_on_index implementation to gitlab.nvim, as I am not sure how often this is actually an issue (require loops). But this can also be solved by adding something like:

M.require_on_index = function(require_path)
  return setmetatable({}, {
    __index = function(_, key)
      return require(require_path)[key]
    end,

    __newindex = function(_, key, value)
      require(require_path)[key] = value
    end,
  })
end

and then doing:

local u = require("gitlab.util.lazy").require_on_index("gitlab.utils")

And since it is not required until it is used, you do not run into the same require looping stuff that causes this to be necessary.