Add a public config folder per addon (#4650)

* Add a public config folder per addon

* Finish addon_configs map option

* Rename map values and add addon_config

tests/fixtures/addon-config-map-addon_config.json

@@ -0,0 +1,14 @@
+{
+  "name": "Test Add-on",
+  "version": "1.0.1",
+  "slug": "test_addon",
+  "description": "This is an Add-on which maps all addon configs",
+  "arch": ["amd64"],
+  "url": "https://www.home-assistant.io/",
+  "startup": "application",
+  "boot": "auto",
+  "map": ["addon_config", "ssl", "media", "share"],
+  "options": {},
+  "schema": {},
+  "image": "test/{arch}-my-custom-addon"
+}