Build: Move out some codes from set_config.cmake

CMake config and Kconfig system will be separated later.
Moving out some common codes from set_config.cmake

- Add pre_config.cmake for common codes
  - Move out platform preload.cmake to pre_config.cmake
  - Move out Library Model deprecation message to pre_config.cmake
  - Move out CMAKE_BUILD_TYPE setup to pre_config.cmake
  - Error checks (Library Model, TFM_SYSTEM_DSP and CMAKE_GENERATOR) are
    gathered together into pre_config.cmake
- Add post_config.cmake for common codes
  - Move out the tfm_config setup from set_config.cmake to
    post_config.cmake.
  - Move out tfm_build_log_config.cmake inclusion to post_config.cmake
  - Move test repo fetch and config are separated and move to
    post_config.cmake

Change-Id: Idf39766d4f7c3e3933443c7eef31b9e0479064ea
Signed-off-by: Kevin Peng <kevin.peng@arm.com>
diff --git a/lib/ext/tf-m-tests/fetch_repo.cmake b/lib/ext/tf-m-tests/fetch_repo.cmake
index a2a12bd..442e924 100644
--- a/lib/ext/tf-m-tests/fetch_repo.cmake
+++ b/lib/ext/tf-m-tests/fetch_repo.cmake
@@ -1,5 +1,5 @@
 #-------------------------------------------------------------------------------
-# Copyright (c) 2020-2022, Arm Limited. All rights reserved.
+# Copyright (c) 2020-2023, Arm Limited. All rights reserved.
 # Copyright (c) 2022 Cypress Semiconductor Corporation (an Infineon company)
 # or an affiliate of Cypress Semiconductor Corporation. All rights reserved.
 #
@@ -33,9 +33,4 @@
     if (NOT TFM_TEST_PATH)
         set(TFM_TEST_PATH ${TFM_TEST_REPO_PATH}/test CACHE PATH "Path to TFM tests" FORCE)
     endif()
-
-    # Load TF-M regression test suites setting
-    if (TFM_NS_REG_TEST OR TFM_S_REG_TEST)
-        include(${TFM_TEST_PATH}/config/set_config.cmake)
-    endif()
 endif()