feat: add proveCashierShard and proveCashierRoot checks

[ihoroleksiienko]

Main changes

Implemented proveCashierShard and proveCashierRoot validation checks in CashierShard and Cashier contracts to verify whether a provided address corresponds to a valid CashierShard or Cashier instance.

New declarations

ICashier interface:

    /**
     * @dev Proves that the contract is the cashier root contract.
     */
    function proveCashierRoot() external pure;

ICashierShard interface:

    /**
     * @dev Proves that the contract is the cashier shard contract.
     */
    function proveCashierShard() external pure;

Test coverage

New functionality was fully covered by tests.

Coverage details

File	% Stmts	% Branch	% Funcs	% Lines
contracts/	100.00	97.75	100.00	100
├─ Cashier.sol	100.00	98.53	100.00	100
├─ CashierShard.sol	100.00	95.24	100.00	100
├─ CashierShardStorage.sol	100.00	100.00	100.00	100.00
├─ CashierStorage.sol	100.00	100.00	100.00	100.00
contracts/base/	100.00	100.00	100.00	100.00
├─ AccessControlExtUpgradeable.sol	100.00	100.00	100.00	100.00
├─ PausableExtUpgradeable.sol	100.00	100.00	100.00	100.00
├─ RescuableUpgradeable.sol	100.00	100.00	100.00	100.00
contracts/interfaces/	100.00	100.00	100.00	100.00
├─ ICashier.sol	100.00	100.00	100.00	100.00
├─ ICashierHook.sol	100.00	100.00	100.00	100.00
├─ ICashierHookable.sol	100.00	100.00	100.00	100.00
├─ ICashierShard.sol	100.00	100.00	100.00	100.00
├─ ICashierTypes.sol	100.00	100.00	100.00	100.00
├─ IERC20Mintable.sol	100.00	100.00	100.00	100.00
contracts/mocks/	100.00	100.00	100.00	100.00
├─ CashierHookMock.sol	100.00	100.00	100.00	100.00
├─ CashierShardMock.sol	100.00	100.00	100.00	100.00
contracts/mocks/base/	100.00	100.00	100.00	100.00
├─ AccessControlExtUpgradeableMock.sol	100.00	100.00	100.00	100.00
├─ PausableExtUpgradeableMock.sol	100.00	100.00	100.00	100.00
├─ RescuableUpgradeableMock.sol	100.00	100.00	100.00	100.00
contracts/mocks/tokens/	100.00	100.00	100.00	100.00
├─ ERC20TokenMock.sol	100.00	100.00	100.00	100.00
---------------------------------------	---------	----------	---------	---------
All files	100.00	98.06	100.00	100
---------------------------------------	---------	----------	---------	---------