ESP32S2 target added to the Espressif port, modified CMakeLists,
and added the bootloader related files to esp32s2 target directory.

Signed-off-by: Almir Okato <almir.okato@espressif.com>

• Commit 23fbd7c
• #1071: ESP32-S2: Basic MCUboot support
• Branch main

almir-okato