Serialization of flagged/bitwise enums

Follow up to https://github.com/microsoft/kiota/issues/3237

Passing over the style(serialization) format information to the serializers would either mean

- Adding an extra style parameter to the getCollectionOfEnumValues/writeCollectionOfEnumValues/writeEnumValue/getEnumValue functions used by the serializers
- Adding new WriteFlaggedEnum/GetFlaggedEnum that takes the style parameter.

Both would be breaking changes as they would introduce a new function to the existing serialization interfaces or change method signatures.

Start by reading issue #3237 and the existing serialization interfaces referenced in this issue. Compare the two proposed approaches for passing style information to enum serializers; the work is complete when a compatible approach for flagged/bitwise enum serialization is agreed and implemented.

Written by the indexing model from the issue text.