Make application and retry fees dynamically fetched

[Tieumsan]

Problem Statement

The fee to pay for the KYC application to get the card might change over the product lifecycle. If we have a value hard-coded on all the client applications, this might bring inconsistencies and misunderstanding the next time we update the application fee (€).

Solution

Rather than relying on hard-coded values, it would make sense to enable to fetch the application fee from the backend.

Requirements

Backend

• [x] Store the application fee in the backend
• [x] Endpoint to fetch the application fee
• [x] https://github.com/soramitsu/sora-card-backend/issues/323

Client Applications

See data structures in backend task and documentation.

• [x] sora-xor/sora-card-android#116
• [x] sora-xor/sora-card-ios#77
• [x] sora-xor/sora-card-web#29

[Alexey-N-Chernyshov]

Added endpoint /fees that returns: {"application_fee":"29","retry_fee":"3.80"}