example/gatt_streamer_server: fix PHY update message

example: use GAP_SUBEVENT_LE_CONNECTION_COMPLETE instead of HCI_SUBEVENT_LE_CONNECTION_COMPLETE

example: use slave latency of 4 to avoid disconnects in some Controller combinations

example: gatt_streamer_server and le_streamer_client report DLE and PHY changes

examples: unify status stdout format

example: remove call to le_device_db_init

license: update text

example: use #define for constants instead of const uint8_t to fix build

example: use AD Flags 0x02 in dual-mode examples

examples: use `btstack_event.h` getters instead of direct array access, use enum to compare status codes

add missing default switch cases

docu: copy editing examples titles

docu: updated titles of examples

examples: renamed le_counter to gatt_counter and le_streamer to le_streamer_server to indicate suppport for GATT over BR/EDR