REX: implement rexmaturity ACTION to allow modifying maturity buckets length of time

[DenisCarriere]

Purpose

Introduce the rexmaturity ACTION to enable modification of the REX maturity buckets length of time (in days).

Feedback provided by

• @DenisCarriere
• @nsjames

rexmaturity ACTION Specification

/**
 * Facilitates the modification of REX maturity buckets
 *
 * @param num_of_maturity_buckets - used to calculate maturity time of purchase REX tokens from end of the day UTC.
 * @param sell_matured_rex - if true, matured REX is sold immediately.
 * @param buy_rex_to_savings - if true, buying REX is moved immediately to REX savings.
 */
[[eosio::action]]
void rexmaturity(const std::optional<uint32_t> num_of_maturity_buckets,
  const std::optional<bool> sell_matured_rex,
  const std::optional<bool> buy_rex_to_savings );

rexmaturity SINGLETON TABLE specification

struct rex_maturity {
  uint32_t num_of_maturity_buckets = 5;
  bool sell_matured_rex = false;
  bool buy_rex_to_savings = false;
};

Preconditions

• Default value num_of_maturity_buckets=5 (4 days)
• num_of_maturity_buckets cannot exceed >30 (will cause limitations in RAM consumption due to bucket creation)

References

• get_rex_maturity()

Note: changes should be pushed to Antelope Reference contracts https://github.com/AntelopeIO/reference-contracts

[DenisCarriere]

Implemented via AntelopeIO/reference-contracts@b694722

Just missing some additional unit tests for this functionality