Admin apis for fees

[altafan]

At the moment, restarting arkd is required to update the fee policies as they can be changed only via env vars.

Let's get rid of the env vars in favor of admin apis so that fee polices can be updated at runtime and prevent any service restart.

This task requires changes at pretty much all layers:

• domain: add IntentFee domain and FeeRepository interface with CRUD apis:

type IntentFees struct {
   OnchainInputFee string
   OffchainInputFee string
   OnchainOutputFee string
   OffchainOutputFee string
}

type FeeRepository interface {
   GetIntentFees(ctx context.Context) (*IntentFees, error)
   UpsertIntentFees(ctx context.Context, fees IntentFees) error
   ClearIntentFees(ctx context.Context) error
   Close()
}

• ports: add Fees() domain.FeeRepository api to repo manager
• infrastructure: add implementations of domain.FeeRepository (badger, sqlite and postgres)
• application: add CRUD apis to admin service for fee management
• interface: add new rpcs GetIntentFees and UpdateIntentFees to admin.proto
• config: drop existing env vars

NOTE: repo.UpsertIntentFees should take care of updating only the non-empty fields defined in the provided struct.

#380 can be taken as reference.

[bitcoin-coder-bob]

@altafan For the infrastructure: add implementations of domain.FeeRepository (badger, sqlite and postgres) is the ask here to make a db table for the intent fees? Maybe something like:

CREATE TABLE IF NOT EXISTS intent_fees (
    id TEXT PRIMARY KEY,
    created_at BIGINT NOT NULL,
    offchain_input_fee_program TEXT NOT NULL DEFAULT '0',
    onchain_input_fee_program TEXT NOT NULL DEFAULT '0',
    offchain_output_fee_program TEXT NOT NULL DEFAULT '0',
    onchain_output_fee_program TEXT NOT NULL DEFAULT '0'
);

[altafan]

@bitcoin-coder-bob in internal/infrastructure/db you can find badger, sqlite and postgresfolders that include the implementations of the repository interfaces defined ininternal/core/domain`.

The idea is to add a new file to those folders containing the impl of the newly interface added to domain.

Your definition of the table looks fine for pg and sqlite. Badger is a kv value store so there's no need for a table (just start from a copy paste of scheduled session repo if you're not confident with it)