chore: remove QuickNav addon from build and loader (#343)

- Remove QuickNav install block from src/Mod/Create/CMakeLists.txt
- Remove mods/quicknav submodule entry from .gitmodules
- Remove quicknav imports and TestWorkbenchMap tests from test_kindred_pure.py
- Remove mods/quicknav submodule from git tracking

QuickNav will be archived to a reference folder in a separate step (#345).
This is part of the UI/UX rework epic (#346).

src/Mod/Create/CMakeLists.txt

@@ -85,22 +85,6 @@ install(
         mods/sdk
 )
 
-# Install QuickNav addon
-install(
-    DIRECTORY
-        ${CMAKE_SOURCE_DIR}/mods/quicknav/quicknav
-    DESTINATION
-        mods/quicknav
-)
-install(
-    FILES
-        ${CMAKE_SOURCE_DIR}/mods/quicknav/package.xml
-        ${CMAKE_SOURCE_DIR}/mods/quicknav/Init.py
-        ${CMAKE_SOURCE_DIR}/mods/quicknav/InitGui.py
-    DESTINATION
-        mods/quicknav
-)
-
 # Install Kindred Solver addon
 install(
     DIRECTORY