Unit tests for HBAR Rate limit

[georgi-l95]

Problem

There are no unit test for the hbar rate limiter. We need to cover this functionality.

Solution

Add unit tests to test shouldLimit, addExpenses, shouldResetLimiter

Alternatives

No response

[Nana-EC]

@georgi-l95 when addressing this can you add logic for

Enable flag that is set to false when a valid HBAR_RATE_LIMIT_TINYBAR and HBAR_RATE_LIMIT_DURATION is not set. This will support enabling and disabling

• add checks for this.enabled in
  • constructor(), if false don't set other variables. This will require other variables to have a default value (mostly 0)
  • shouldLimit(), if false return false
  • addExpense() if false don't decrement