Enable neovim through home-manager

- We need to set the default editor to just "nvim" not a particular path, as
  this allows us to override nvim in our home
- Add the mapleader bind to the start of init.vim
- As the leader is interpreted whenever we make a keybind, we must have it at
  the start or it won't be respected for some of our keybinds (but will be for
  others)
- Package the scrollbar plugin and install it
- Setup configs for stuff like treesitter, theme, COC, scrollbar etc.
- Add git capabilities to neovim
- Install fugitive, gitgutter and git-conflict, along with some other basic git
  stuff
- Allow mouse control in neovim
diff --git a/modules/neovim/airline/tabline.vim b/modules/neovim/airline/tabline.vim
new file mode 100644
index 0000000..9ff7315
--- /dev/null
+++ b/modules/neovim/airline/tabline.vim
@@ -0,0 +1,16 @@
+let g:airline#extensions#tabline#enabled = 1
+let g:airline#extensions#tabline#formatter = 'unique_tail_improved'
+let g:airline#extensions#tabline#buffer_idx_mode = 1
+
+nmap <leader>1 <Plug>AirlineSelectTab1
+nmap <leader>2 <Plug>AirlineSelectTab2
+nmap <leader>3 <Plug>AirlineSelectTab3
+nmap <leader>4 <Plug>AirlineSelectTab4
+nmap <leader>5 <Plug>AirlineSelectTab5
+nmap <leader>6 <Plug>AirlineSelectTab6
+nmap <leader>7 <Plug>AirlineSelectTab7
+nmap <leader>8 <Plug>AirlineSelectTab8
+nmap <leader>9 <Plug>AirlineSelectTab9
+nmap <leader>0 <Plug>AirlineSelectTab0
+nmap <leader>- <Plug>AirlineSelectPrevTab
+nmap <leader>+ <Plug>AirlineSelectNextTab