External apps (#1469)

* implemented external app build

* added some ui stuff for testing

* added pacman game

* wired key to pacman game

* fixed pacman drawing issue

* changed afsk rx app to be external

* fixed ui::NavigationView initialization for external apps

* refactoring

* refactoring

* moved m4 image to external app

* added script for external app deployment

* refactoring

* implemented dynamic app listing

* added color to app icon

* improved app loading

* added external apps to sd card content

* refactoring

* review findings

* typo

* review findings

* improved memory management of bitmaps

firmware/application/external/external.ld

@@ -0,0 +1,37 @@
+/*
+    Copyright (C) 2023 Bernd Herzog
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+        http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+*/
+
+MEMORY
+{
+    /* external apps: regions can't overlap so addresses are corrected after build */
+    ram_external_app_pacman     (rwx) : org = 0xEEE90000, len = 40k
+    ram_external_app_afsk_rx    (rwx) : org = 0xEEEA0000, len = 40k
+}
+
+SECTIONS
+{
+    .external_app_pacman : ALIGN(16) SUBALIGN(16)
+    {
+        KEEP(*(.external_app.app_pacman.application_information));
+        *(*ui*external_app*pacman*);
+    } > ram_external_app_pacman
+
+    .external_app_afsk_rx : ALIGN(16) SUBALIGN(16)
+    {
+        KEEP(*(.external_app.app_afsk_rx.application_information));
+        *(*ui*external_app*afsk_rx*);
+    } > ram_external_app_afsk_rx
+}