* General code cleanup
* The internal data struct type `BeaconData` is now public and can be used by the application.
* `NimBLEBeacon::setData` now takes `const NimBLEBeacon::BeaconData&` instead of `std::string`.
* Added overload for `NimBLEBeacon::setData` that takes a pointer to raw `uint8_t` data and length`.
* `NimBLEBeacon::getData` now returns `const NimBLEBeacon::BeaconData&` instead of `std::string`.
This allows NimBLE options in menuconfig to reduce code size based on
the roles selected (scan/advertising/central/peripheral).
Significant code space can be saved by removing unnecessary roles for the application.
