[refactor]: split `SerializationFormat` into two properties of `WireInformation`

### Clear and concise description of the problem

This derives from review of PR #4186. Our `SerializationFormat` enum is a combination of source data type and target encoding. We should remove `SerializationFormat`, move those two properties into `WireInformation`.

### Checklist

- [X] Follow our [Code of Conduct](https://github.com/microsoft/typespec/blob/main/CODE_OF_CONDUCT.md)
- [X] Read the [docs](https://typespec.io/docs/).
- [X] Check that there isn't already an issue that request the same feature to avoid creating a duplicate.