Add SD theme system

Adds installable SD-card themes with manifest downloads, theme registry parsing, themed home/chrome/settings/file browser support, FreeInk layout integration, theme documentation, and layout tests.

test/theme_layout/CMakeLists.txt

@@ -0,0 +1,16 @@
+add_executable(ThemeLayoutTest
+  ThemeLayoutTest.cpp
+  ${REPO_ROOT}/src/components/themes/ThemeLayout.cpp
+)
+
+target_include_directories(ThemeLayoutTest PRIVATE
+  ${REPO_ROOT}/src
+  ${REPO_ROOT}/freeink-sdk/libs/ui/FreeInkUI/include
+)
+
+target_link_libraries(ThemeLayoutTest PRIVATE
+  crosspoint_test_common
+  GTest::gtest_main
+)
+
+gtest_discover_tests(ThemeLayoutTest)