[Mex-666] : Split Fiat and Crypto in Redis and use USDC as USD equivalent

[EmanuelMiron]

Reasoning

• USD values in the backend service are reffered to USDC value rather than the USD value
• Crypro Rates are more subjective to cahnge rather than the Fiat rates and they were updated on the same interval

Proposed Changes

• use USDC to calculate crypto rates
• Split FIAT and Crypto rates in Redis

How to test

currencyRates (symbols: ["EGLD", "WBTC", "WETH", "EUR"]) {
      symbol
      rate
      category
      name
    }

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 52.81%. Comparing base (87683b0) to head (6056068).
Report is 41 commits behind head on development.

Additional details and impacted files

@@               Coverage Diff               @@
##           development    #1564      +/-   ##
===============================================
- Coverage        52.90%   52.81%   -0.09%     
===============================================
  Files              269      270       +1     
  Lines            10656    10693      +37     
  Branches           825      827       +2     
===============================================
+ Hits              5638     5648      +10     
- Misses            4278     4303      +25     
- Partials           740      742       +2     

Flag	Coverage Δ
unittests	52.81% <ø> (-0.09%)	⬇️

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