feat(vim): add prr plugin for a better code review experience

Sets code folding of diffs and hunks so we can review hunks on there
own. This is good for larger pull requests, you can focus on the hunk
and not get overwhelmed by the rest of the code.

Adds a go to definition mapping for prr lines. This will allow you to go
straight to the line of code when reviewing a pull request. Seeing the
code in full context is really helpful when reviewing. You are then
there in your editor with all the linters and the LSP.

site-modules/core/files/vim/ftplugin/prr.vim

@@ -0,0 +1,31 @@
+"
+" function for the `foldexpr` to fold git diffs and hunks
+"
+" Inspired from https://github.com/sgeb/vim-diff-fold
+"
+function! s:fold_diff_hunk()
+    let l:line=getline(v:lnum)
+
+  if l:line =~# '^> \(diff\|Index\)'
+        return '>1'
+    elseif l:line =~# '^> \(@@\|\d\)'
+        return '>2'
+    elseif l:line =~# '^> \*\*\* \d\+,\d\+ \*\*\*\*$'
+        return '>2'
+    elseif l:line =~# '^> --- \d\+,\d\+ ----$'
+        return '>2'
+    else
+        return '='
+    endif
+endfunction
+
+setlocal foldenable
+setlocal nomodeline formatoptions-=croq formatoptions+=tl
+setlocal foldmethod=expr
+setlocal foldexpr=s:fold_diff_hunk()
+setlocal foldlevel=99
+
+" Add "go to definition" mapping for prr lines. This will allow you to go to
+" the line of code when reviewing a pull request. Seeing the code in full
+" context is really helpful when reviewing.
+noremap <silent> gd :PrrGoToLine<cr>

site-modules/core/files/vim/plugin/prr.lua

@@ -0,0 +1,26 @@
+vim.api.nvim_create_user_command("PrrGoToLine", function()
+  local content = vim.api.nvim_buf_get_lines(0, 0, -1, false)
+  local line, column = unpack(vim.api.nvim_win_get_cursor(0))
+
+  local target_file = ""
+  local target_line = 0
+
+  for i = 1, line do
+    local line_content = content[i]
+    local file_match = line_content:match "> diff .* b/(.*)"
+    if file_match ~= nil then
+      target_file = file_match
+    end
+
+    local line_match = line_content:match "+(%d+)"
+    if line_match ~= nil then
+      target_line = line_match
+    elseif line_content:match "> (-).*" == nil then
+      target_line = target_line + 1
+    end
+  end
+
+  vim.cmd("e " .. target_file)
+  vim.fn.cursor(target_line - 1, column)
+end, { bang = true, desc = "Open the current file at the poin in a prr buffer" })
+