Contracts should be able to report their own schema

[egasimus]

Some trickery may be required to include the results of cosmwasm_schema into the contract. Might be easier to tackle this via the contract macro.

[aakamenov]

As of now it is currently impossible to serialize the schema object into a string. The currently used version of serde_json_wasm in CW 1.1.9 is 0.4.1 which doesn't even support maps. But even when using 0.5.0 which does we run into the dreaded floating point issue. So I can see several options:

• Wait until enum support in serde_json_wasm just works™ (which might be never not very soon from the looks of it) .
• Slap together some hack to serialize the schemars object into a valid JSON schema, but:
  • This means that we have to add code to the core crate just to support this.
  • The DSL macro crate becomes dependent on Fadroma.
  • Needs more research into how feasible this even is.
  • It is a hack...
• Come up with our own format which also has it's problems and downsides:
  • Obviously needs the most thought and work put into it.
  • It needs to be decided whether the format would be human or machine focused. Currently, the interface of a contract can only be inferred by guessing. It would be nice to have a nice and concise human-readable representation which JSON schema is not. On the other hand we want tools to be able to validate it. We will need client-side parsers if that's the case...
  • This introduces our own format and we have require people to derive it for their types (even if it's automatic). We are already doing this for the binary ser/de but I'd argue that the case for that is MUCH stronger than it is for this.