Service provider directory support in nym-api, nym-cli, validator-client

[octol]

Description

Closes: #3296
Closes: #3241
Closes: #3242
Closes: #3334

• Add sp directory contract traits and methods to nyxd client
• Make the contract optional
• nym-api: add service provider endpoint and caching
• nym-cli: add query, announce and delete service provider

[octol]

The way we should test this IMHO is the following:

1. Deploy nym-api from this branch, and make sure it works with qwerty where the service provider contract is already deployed, but crucially also that it works with mainnet where there is no contract yet. The service provider contract is supposed to be optional so we don't want anything breaking for networks where it's missing.
   1. For qwerty I'd expect the endpoints for the nym-api to be able to query announced services
   2. For mainnet, the endpoint should be there but it should return an empty list
   3. Announcing and deleting services is done via the nym-cli
2. Once the above is cleared, I think we should merge it into the release branch
3. When it's merged into the release branch we can start doing further more extensive testing of the service-provider contract in itself (which can be a follow up task)

[jstuczyn]

lgtm

[jstuczyn]

I wonder if it would make sense to change the deposit to be an explicit Coin so people wouldnt be confused by unym vs nym. But it's more of a note for the future