[py-tx] Upvote/Downbote/Matched Interfaces

[Dcallies]

Add a SignalType interface for:

1. Upvote/Downvote - aka Review Feedback
2. Matched on platform - previously described as "seen"
3. Upload

Which can be implemented by the existing interfaces. As of issue creation, there are multiple unsolved challenges with what this interface should be, due to the heterogeneous nature of the different interfaces.

Of these, the easiest to handle is "Upload", since it can be done without worrying about the key type.

Likely the easiest way to attempt this:

1. Split up the implementation of these methods between File (for testing), ThreatExchange, StopNCII, and NCMEC
2. Implement the correct functionality in each of the clients first (e.g. the correct post requests)
3. Come back together and find the minimum interface that satisfies all the inputs needed for each API

Attempted in #1630, but let's wait on the sub-issues first.