Add support for getting multiple services data from advertisments. (#89)

* Add support for getting multiple services data from advertisments.

* Adds new methods for getting advertised service data and UUIDS.
- getServiceData(index), gets the service data by index value.
- getServiceData(NimBLEUUID), gets the service data by UUID.
- getServiceDataCount(), gets the number of services with data advertised.

* Templates added for getServiceData(index) and getServiceData(NimBLEUUID)
  to be able to specify the data type returned by these methods
  Example:
      getServiceData<uint32_t>(NimBLEUUID("ABCD");

* Also added:
- getServiceUUID(index), gets the advertised service UUID by index value.
- getServiceUUIDCount(), gets the number of advertised services.

Author: h2zero