Add decoration of runtimeApis

[TarikGul]

rel: #5725

The next step in getting runtimeApis from the metadata is to have them decorated at runtime via the metadata. This can be seen as similar to decorateExtrinsics. This should only be available for V15.

Once this issue is complete we can then add it to the static typegen.

[TarikGul]

This would actually replace decorateCalls inside of the api base decoration.