cmake: move host-tool loading from Zephyr-sdk into COMPONENTS

Move loading of Zephyr-sdk host tools cmake file from Zephyr into
Zephyr SDK itself.

This allows us to cleanup Zephyr CMake code as well as place the
responsibility of checking and loading host tools when available.

This removes the need for custom printing as CMake find_package()
provides this functionality built-in, as well as ensuring uniform
message formatting and general package handling.

It further remove the confusing message:
> -- Found host-tools: zephyr 0.15.0 (/opt/zephyr-sdk-0.15.0)
which is printed even when host tools are not installed.

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

Author: tejlmand

cmake/modules/FindZephyr-sdk.cmake

@@ -59,6 +59,7 @@ if(("zephyr" STREQUAL ${ZEPHYR_TOOLCHAIN_VARIANT}) OR
     set(ZEPHYR_CURRENT_TOOLCHAIN_VARIANT ${ZEPHYR_TOOLCHAIN_VARIANT})
     find_package(Zephyr-sdk ${Zephyr-sdk_FIND_VERSION}
                  REQUIRED QUIET CONFIG HINTS ${ZEPHYR_SDK_INSTALL_DIR}
+                 COMPONENTS HostTools
     )
     if(DEFINED ZEPHYR_CURRENT_TOOLCHAIN_VARIANT)
       set(ZEPHYR_TOOLCHAIN_VARIANT ${ZEPHYR_CURRENT_TOOLCHAIN_VARIANT})
@@ -71,7 +72,9 @@ if(("zephyr" STREQUAL ${ZEPHYR_TOOLCHAIN_VARIANT}) OR
                  $ENV{HOME}
                  $ENV{HOME}/.local
                  $ENV{HOME}/.local/opt
-                 $ENV{HOME}/bin)
+                 $ENV{HOME}/bin
+                 COMPONENTS HostTools
+    )
   endif()
 
   SET(CMAKE_FIND_PACKAGE_SORT_DIRECTION ${CMAKE_FIND_PACKAGE_SORT_DIRECTION_CURRENT})
@@ -83,7 +86,8 @@ if(DEFINED ZEPHYR_SDK_INSTALL_DIR)
   set(ZEPHYR_SDK_INSTALL_DIR ${ZEPHYR_SDK_INSTALL_DIR} CACHE PATH "Zephyr SDK install directory")
 endif()
 
-if(Zephyr-sdk_FOUND)
+if(Zephyr-sdk_FOUND AND Zephyr-sdk_VERSION VERSION_LESS_EQUAL 0.15.0)
+  # Older Zephyr SDKs doesn't support COMPONENT HostTools so must manually be loaded.
   include(${ZEPHYR_SDK_INSTALL_DIR}/cmake/zephyr/host-tools.cmake)
 
   message(STATUS "Found host-tools: zephyr ${SDK_VERSION} (${ZEPHYR_SDK_INSTALL_DIR})")