[BREAKING CHANGE] Change RawValue API - create RawValue directly from Payload

[THardy98]

What was changed

Changes the RawValue API. Formerly, you could create a RawValue from any given value via the constructor. However, it was not possible to create a RawValue directly with a payload.

This PR changes the API to instead:

• allow RawValue to be created directly from a payload, via its constructor (changing the constructor signature is the breaking change)
• all RawValue to still be created with any given value, via a static method fromValue

Why?

Imo, this API makes more sense. If we wanted to keep the old API, but expand it to include a static for fromPayload it would probably look something like this:

  static fromPayload<T = unknown>(payload: Payload): RawValue<T> {
      const instance = Object.create(RawValue.prototype) as RawValue<T>;
      (instance as any)._payload = payload;
      return instance;
  }

which isn't very nice, despite being a basic case.

alternatively, we could expand the type of the value in the constructor to T | Payload and add some type guard checks. Also not very nice, imo.

2. How was this tested:
   Updated existing tests.

3. Any docs updates needed?
   Not sure

[THardy98]

Not really expecting this to be merged or anything (at least, not without discussion). Mostly want to put this up for awareness. I'm ok with the other options as well, but I do think this is missing functionality.