Addon Manager: Begin UI redesign

Migrate to a UI that looks more like other software package managers, giving
more space to each addon by hiding the list when an addon is selected, and
providing a "back" button to get back.

Implements a two-style view option for the list of addons: expanded and
condensed, via a delegate that provides the drawing function for each row in
the table based on two different widget designs.

src/Mod/AddonManager/addonmanager_macro.py

@@ -26,6 +26,7 @@ import re
 import sys
 import codecs
 import shutil
+from typing import Dict, Union
 
 import FreeCAD
 
@@ -63,6 +64,18 @@ class Macro(object):
     def __eq__(self, other):
         return self.filename == other.filename
 
+    @classmethod
+    def from_cache (self, cache_dict:Dict):
+        instance = Macro(cache_dict["name"])
+        for key,value in cache_dict.items():
+            instance.__dict__[key] = value
+        return instance
+
+    def to_cache (self) -> Dict:
+        """ For cache purposes this entire class is dumped directly """
+
+        return self.__dict__
+
     @property
     def filename(self):
         if self.on_git: