Support Hook Functions (RDT-625)

[hfudev]

Support hook functions in idf-build-apps

A few ideas with the hook functions:

• pre_build
  • prepare_sdkconfig_files (check config_rules_str, check override_sdkconfig options, etc)
  • some checks
• build
• post_build
  • parse_build_warnings_and_errors
  • some extra file system operations, like rename, move, remove some files, keep only bin files, etc)

To increase the flexibility, we may use the hook system that pytest uses: https://github.com/pytest-dev/pluggy

Or a more conservative choice, provide more decoupled functions, then users may use the method overriding way to achieve the same goal.