This commit refactors the esptool_py component to provide utility
functions for flash target management instead of creating the targets
directly. Flash target creation is now moved to the project level in
build.cmake file when idf_build_executable() runs.
The following changes were done in this commit:
- Added __esptool_py_setup_tools(), __esptool_py_setup_estool_py_args()
and __ensure_esptool_py_setup() functions to centralize esptool_py
setup.
- Added __esptool_py_setup_main_flash_target() which is called by
idf_build_executable() to create the flash targets.
- Updated esptool_py_flash_target(), esptool_py_custom_target() to
accept an optional FILENAME_PREFIX argument to enable creation of
build artifacts based on custom names.
- Create placeholder flash targets early in the build process when
idf_build_process() is called for components to add dependencies on
these targets.
- Moved app-flash target creation from esptool_py/CMakeLists.txt to
build.cmake.
- Added function description to esptool_py functions.