refactor: implement modular plugin structure

lua/custom/plugins/git.lua

@@ -0,0 +1,19 @@
+--[plugins/git.lua]
+
+return {
+    { -- Adds git related signs to the gutter, as well as utilities for managing changes
+        'lewis6991/gitsigns.nvim',
+        opts = {
+            signs = {
+                add = { text = '+' },
+                change = { text = '~' },
+                delete = { text = '_' },
+                topdelete = { text = '‾' },
+                changedelete = { text = '~' },
+            },
+        },
+    },
+
+    -- This loads the keymaps from the separate gitsigns.lua file
+    require('plugins.gitsigns'),
+}