* Add keymap API for getting/setting a bindings
in keymap layers.
* Add layer move support via intemediary ordering array.
* Add settings storage for keymap changes.
* UART and BLE/GATT transports for a protobuf encoded RPC
request/response protocol.
* Custom framing protocol is used to frame a give message.
* Requests/responses are divided into major "subsystems" which
handle requests and create response messages.
* Notification support, including mapping local events to RPC
notifications by a given subsystem.
* Meta responses for "no response" and "unlock needed".
* Initial basic lock state support in a new core section, and allow specifying
if a given RPC callback requires unlocked state or not.
* Add behavior subsystem with full metadata support and examples of
using callback to serialize a repeated field without extra stack space needed.
Co-authored-by: Cem Aksoylar <caksoylar@users.noreply.github.com>
