Presentation: Update addon serializer to serialize nodes and node path elements in expected format

[grigasp]

In TS we expect:

• Node label to be defined as label attribute, but addon serializes it as labelDefinition.

  Workaround: https://github.com/iTwin/itwinjs-core/blob/7545df3819dcf0efaa525c660cf05b61971a6ad7/presentation/backend/src/presentation-backend/PresentationManagerDetail.ts#L645-L654

• NodePathElement.filteringData to be in NodePathFilteringData format, but it's { childrenOccurances: number; occurances: number; }.

  Workaround: https://github.com/iTwin/itwinjs-core/blob/7545df3819dcf0efaa525c660cf05b61971a6ad7/presentation/backend/src/presentation-backend/PresentationManagerDetail.ts#L625-L636

Need to update the addon to serialize in proper formats, and remove the workarounds.