RDKCOM-5487: RDKBWIFI-206: add mocks, build, and limited platform independent L1 tests

[fwph]

This PR creates a set of L1 unittests for limited set of functions in the file source/core/wifi_ctrl_webconfig.c

The tests emphasize pointer safety to capture inputs which are currently at risk for null pointer dereferences. In order to support the tests, the following changes have been made to the build:

• .github/workflows/makefile.yml has been updated to add an additional platform (mockplatform) in the strategy matrix build/linux/bpi/makefile and build/linux/rpi/makefile have been updated to accommodate the split
• source/test/platform_mocks.c has been added to implement platform-specific functions in lieu of the raspberrypi/bananapi functions from $(WIFI_RDK_HAL)/platform

This PR uses objcopy to create a version of the object file with the main symbol stripped out from wifi_mgr.o before linking the gtest binary.

Unit test notes:

• WifiCtrlWebconfig.DISABLED_VifNeighborsApplyHappyPathCheckDestroyedMapPtr is currently disabled because webconfig_vif_neighbors_apply frees the data member of the argument webconfig_subdoc_decoded_data_t *data but does not set the member to NULL after the free, leaving the invalid pointer.

• The other tests focus on exercising the logic updated by:

  • RDKBWIFI-198: wifi_ctrl_webconfig: add null check for data #692
  • RDKBWIFI-199: wifi_ctrl_webconfig: add null check for data #693
  • RDKBWIFI-200: wifi_ctrl_webconfig: add null check for data #694
  • RDKBWIFI-201: wifi_ctrl_webconfig: add null check for data #695

on-behalf-of: @permanence-ai github-ai@permanence.ai