Merge the changes of build system on feature-twincpu back to master branch.
The patch set may include the following features:
- Definitions of multi-core specific option TFM_MULTI_CORE_TOPOLOGY. The specific name can be discussed and determined during review.
- Support of building secure firmware and app in single build execution, with different secure and non-secure configs.
The support to PSoC 6 build should be merged with PSoC platform support patch set.