Add RawValue support for non-converted Payloads

[THardy98]

What was changed

Added RawValue support for non-converted Payloads - a thin wrapper around Payload.

RawValue is intended to be used for payloads that bypasses users custom payload converters in favour of the default payload converter.

TS does not include type hints or similar when converting from a payload back to its original representation. As such, the best we can do is just send the payload as is and have users convert it back to its original representation.

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The existing builtin queries now return a RawValue that wraps their former returned values. The return types of the builtin queries however, maintain their existing type (this is because receivers of these queries will get the payload itself, not the RawValue). This is breaking change as consumers of these builtin queries will need to make sure they decode the builtin payloads correctly.

1. Closes [Feature Request] Support "RawValue" non-converted values #1629, [Feature Request] Built-in query responses should use "RawValue" #1630

2. How was this tested:
   Added short integration test, modified the existing built-in metadata test.

3. Any docs updates needed?
   Possibly. Maybe for the change to the built-in metadata query.

[mjameswh]

I believe we need to return RawValue from all built-in queries, not only the user metadata query. And we should be using the default payload converter, not the payload converter provided by the user.

[mjameswh]

I'm really not clear how RawValue should work in TS on the inbound path, given that we don't have any form of type hint on functions that receive Payloads. Using a rawValue payload metadata set on the outbound feels totally wrong to me, as that makes RawValue a symetric thing (i.e. receiver will get a RawValue if and only if the caller sent a RawValue) whereas it seems to me that the reason to have RawPayloads is specifically to support cases where the caller and receiver would have different configurations.

For now, I'd focus on the outbound path only, simply to support return value of built-in queries. For inbound payloads, that might have to wait only we add support for type hints on receivers.

[THardy98]

I've written this in the PR description:

The existing builtin queries now return a RawValue that wraps their former returned values. The return types of the builtin queries however, maintain their existing type (this is because receivers of these queries will get the payload itself, not the RawValue). This is breaking change as consumers of these builtin queries will need to make sure they decode the builtin payloads correctly.

Let me know if this makes sense to you.