Build: Configuration for Regression IPC test

- Disable Regression in ConfigCoreIPC.cmake and
  ConfigCoreIPCTfmLevel2.cmake.
- Add new build configuration to run regresstion with IPC model and IPC
  model isolation level 2.
- Add explicit setting for basic project build variables in all build
  configurations

Change-Id: I9a627ca08209a5b8e295c3cac9538d6e80f2e669
Signed-off-by: Edison Ai <edison.ai@arm.com>
diff --git a/ConfigRegression.cmake b/ConfigRegression.cmake
index 7fdeb93..af0eb9c 100644
--- a/ConfigRegression.cmake
+++ b/ConfigRegression.cmake
@@ -28,6 +28,7 @@
 #definitions) based on these.
 set (REGRESSION True)
 set (CORE_TEST False)
+set (CORE_IPC False)
 set (PSA_API_TEST False)
 
 # TF-M isolation level: 1..3