BREAKING CHANGE: Delta Pager + Large Refactor (#43)

BREAKING CHANGE: This MR addresses an underlying issue with the original implementation in regards to detecting line numbers for comments. 

As such, this is a major breaking change. The setup function signature has changed, please review the `README.md` for the new arguments. The delta pager has also been added as a dependency: https://github.com/dandavison/delta

There will be future work to implement a native solution for parsing changes and line numbers.

lua/gitlab/actions/approvals.lua

@@ -0,0 +1,13 @@
+local job = require("gitlab.job")
+
+local M = {}
+
+M.approve = function()
+  job.run_job("/approve", "POST")
+end
+
+M.revoke = function()
+  job.run_job("/revoke", "POST")
+end
+
+return M