Rewrite keymap.lua (#452)

* Move feedkeys related codes to `cmp.utils.feedkeys`

* Improve mapping handling

* Fix test

* fmt

lua/cmp/utils/keymap_spec.lua

@@ -17,23 +17,6 @@ describe('keymap', function()
     assert.are.equal(keymap.escape('<LT>C-d>'), '<LT>C-d>')
   end)
 
-  describe('feedkeys', function()
-    it('dot-repeat', function()
-      keymap.feedkeys(keymap.t('iaiueo<Esc>'), 'nx')
-      assert.are.equal(vim.fn.getreg('.'), keymap.t('aiueo'))
-    end)
-    it('macro', function()
-      vim.fn.setreg('q', '')
-      vim.cmd([[normal! qq]])
-      keymap.feedkeys(keymap.t('iaiueo'), 'nt')
-      keymap.feedkeys(keymap.t('<Esc>'), 'nt', function()
-        vim.cmd([[normal! q]])
-        assert.are.equal(vim.fn.getreg('q'), keymap.t('iaiueo<Esc>'))
-        print(vim.fn.getreg('q'))
-      end)
-    end)
-  end)
-
   describe('evacuate', function()
     before_each(spec.before)