sysbuild: Use UTF-8 encoding for cache

Fixes an issue whereby strings are placed in UTF-8 format but the
application doesn't read them in when configured using sysbuild
and another issue whereby sysbuild then reads the application's
cache and did not treat them as UTF-8

Signed-off-by: Jamie McCrae <jamie.mccrae@nordicsemi.no>

cmake/modules/basic_settings.cmake

@@ -23,7 +23,7 @@ include_guard(GLOBAL)
 
 if(SYSBUILD)
   add_custom_target(sysbuild_cache)
-  file(STRINGS "${SYSBUILD_CACHE}" sysbuild_cache_strings)
+  file(STRINGS "${SYSBUILD_CACHE}" sysbuild_cache_strings ENCODING UTF-8)
   foreach(str ${sysbuild_cache_strings})
     # Using a regex for matching whole 'VAR_NAME:TYPE=VALUE' will strip semi-colons
     # thus resulting in lists to become strings.

share/sysbuild/cmake/modules/sysbuild_extensions.cmake

@@ -20,7 +20,7 @@ function(load_cache)
   if(NOT TARGET ${LOAD_CACHE_IMAGE}_cache)
     add_custom_target(${LOAD_CACHE_IMAGE}_cache)
   endif()
-  file(STRINGS "${LOAD_CACHE_BINARY_DIR}/CMakeCache.txt" cache_strings)
+  file(STRINGS "${LOAD_CACHE_BINARY_DIR}/CMakeCache.txt" cache_strings ENCODING UTF-8)
   foreach(str ${cache_strings})
     # Using a regex for matching whole 'VAR_NAME:TYPE=VALUE' will strip semi-colons
     # thus resulting in lists to become strings.