cmake: support ZephyrBuildConfiguration_ROOT for package location

Fixes: zephyrproject-rtos#35890

The current implementation of Zephyr build configuration CMake package
only allows the build configuration package to be placed inside a
Zephyr workspace.

This commit extends the usability by allowing users to locate the
Zephyr build configuration CMake package outside the Zephyr workspace
and then refer to the package using
`-DZephyrBuildConfiguration_ROOT=<path>`
`set(ZephyrBuildConfiguration_ROOT <path>)`

This allows users greater flexibility in their workspace layouts.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

cmake/app/boilerplate.cmake

@@ -128,7 +128,17 @@ if((NOT DEFINED ZEPHYR_BASE) AND (DEFINED ENV_ZEPHYR_BASE))
   set(ZEPHYR_BASE ${ENV_ZEPHYR_BASE} CACHE PATH "Zephyr base")
 endif()
 
-find_package(ZephyrBuildConfiguration NAMES ZephyrBuild PATHS ${ZEPHYR_BASE}/../* QUIET NO_DEFAULT_PATH NO_POLICY_SCOPE)
+find_package(ZephyrBuildConfiguration
+  QUIET NO_POLICY_SCOPE
+  NAMES ZephyrBuild
+  PATHS ${ZEPHYR_BASE}/../*
+  NO_CMAKE_PATH
+  NO_CMAKE_ENVIRONMENT_PATH
+  NO_SYSTEM_ENVIRONMENT_PATH
+  NO_CMAKE_PACKAGE_REGISTRY
+  NO_CMAKE_SYSTEM_PATH
+  NO_CMAKE_SYSTEM_PACKAGE_REGISTRY
+)
 
 # Note any later project() resets PROJECT_SOURCE_DIR
 file(TO_CMAKE_PATH "${ZEPHYR_BASE}" PROJECT_SOURCE_DIR)