1. rename linker files
2. support memory release in case that ESP_ALLOW_BSS_SEG_EXTERNAL_MEMORY is enabled
3. improve the implementation of memory release
1. Closes https://github.com/espressif/esp-idf/issues/10427
2. add two linker script to unify linker script symbols for BT libraries
3. The memory release functions have also been simplified
fix(bt): remove unused file linker.lf