gatt_client: drop gatt_client_pts_suppress_mtu_exchange function, replaced by gatt_client_mtu_enable_auto_negotiation(0)

gatt_client: Adds configuration for when or if a MTU negotiation should be made.

- Disable automatic MTU negotiation for gatt_client. Add method to manually
send a MTU negotiation

gatt_client: add gatt_client_stop_listening_for_characteristic_value_updates

doc: tidy function signature, improve api parser

gatt_client: store notification callback, fix characteristic serialization. ancs_client: also listen for notification source notifications

gatt_client: drop packet handler for gatt_client_write_value_of_characteristic_without_response

use hci_con_handle_t more

use hci_con_handle_t more

event: support Service, Characteristic, Characteristic Descriptor in event generator needed for GATT Events. use new getter in examples

gatt_client: extract functions to deserialize gatt client structs and provide in gatt_client

gatt_client: prefix gatt structs with gatt_client

gatt_client: drop subclient struct and id. pass in callback for requests. new gatt_client_listen_for_characteristic_value_updates for notifications and indications with client provided storage

gatt_client: use btstack_packet_handler instead of (*fn)(type,packet,size) for events

use for event types

prefix data_source_t and timer_source_t with btstack

prefixed all linked list types and functions with btstack_

replace le_command_status_t with regular Bluetooth uint8_t error codes, add le_command_status_t enums to error list

split sources into core, ble, and classic