Optimize TokenBalancesController and TokenRatesController

[tommasini]

Description

This issue aims to optimize the TokenBalancesController and TokenRatesController on the assets-controller.
Now, both controllers are fetching the balance and rates multiple times in a few seconds with the mobile app.

We need to debug and refactor them keeping in mind they are not only used for the mobile app.

There are more details in this document.

Technical Details

TokenRatesController

Option1:

• Implement a mutex on TokenRatesController on fetchAndUpdateExchangeRates

Option2:

• Implement all the situations that we would need for the fetchAndUpdateExchangeRates to be called.

TokenBalancesController

• Try the same options as of TokenRatesController

Acceptance Criteria

• Endpoints do not fail because are being requested too many times
• UI/UX of the token list improved thanks to this performance optimization.

Scenario: User detect tokens on mainnet

• GIVEN a user have 15 tokens to detect
• WHEN a user detect that tokens
• THEN Token native and fiat balance should not fail to fetch.

References

• References go here.
• Issue numbers. Links.
• Slack threads.
• Etc.

[gauthierpetetin]

Suggestions:

Split this ticket into 2 tickets:

• One for TokenRatesController
• One for TokenBalancesController

Make a choice between:

• Option1 [best option if it works] - The function is locked while we do a request.
• Option2 - Audit the mobile app code to understand why we use it at different places in the application, then reduce the number.

[tommasini]

For Token Rates Controller -> #6100
For Token Balances Controller -> #6101