Health 12/1097 Lean Body Mass Type

[iarata]

• Adds Lean body mass data type to health (both iOS and Android)

---

Current issues:
The data type can be written, however, when reading back the lean_body_mass it is not able to convert to json (some values result in null).

flutter: Exception in printDataPoint: Converting object to an encodable object failed: Instance of 'HealthDataPoint'

Debug Execpetion:

#0      _JsonStringifier.writeObject (dart:convert/json.dart:793:7)
#1      _JsonStringStringifier.printOn (dart:convert/json.dart:982:17)
#2      _JsonStringStringifier.stringify (dart:convert/json.dart:967:5)
#3      JsonEncoder.convert (dart:convert/json.dart:345:30)
#4      toJsonString (package:carp_serializable/carp_serializable.dart:230:39)
#5      _HealthAppState.fetchData (package:health_example/main.dart:183:20)
<asynchronous suspension>

...

cause = _TypeError (Null check operator used on a null value)

...

unsupportedObject = HealthDataPoint (HealthDataPoint -
    uuid: 44710870-DF07-4F75-A5F7-CB7DECC26AAD,
    value: NumericHealthValue - numericValue: 22.0,
    unit: KILOGRAM,
    dateFrom: 2025-01-05 16:20:26.074,
    dateTo: 2025-01-05 16:40:26.074,
    dataType: LEAN_BODY_MASS,
    platform: HealthPlatformType.appleHealth,
    deviceId: 60569EED-5777-4644-ABFB-C4014B0880BE,
    sourceId: dk.cachet.example,
    sourceName: health_example
    recordingMethod: RecordingMethod.automatic
    workoutSummary: null
    metadata: null)

@SlimShadyIAm Any idea why this is happening, given that there are other instances of HealthDataPoint such as SLEEP_DEEP with the way they're added to the records:

success &= await Health().writeHealthData(
        value: 0.0,
        type: HealthDataType.SLEEP_DEEP,
        startTime: earlier,
        endTime: now);
success &= await Health().writeHealthData(
      value: 22, 
      type: HealthDataType.LEAN_BODY_MASS, 
      startTime: earlier,
      endTime: now);

[iarata]

Closes #1078