feat: remove explicit rounding from getClaimPreview function

[igorsenych-cw]

Main changes

1. The getClaimPreview function has been updated by removing a bool round parameter:

    /**
     * @dev Provides a preview of the claimable yield for a given account at the current time.
     * Estimates the yield amount that can be claimed without modifying the contract state.
     *
     * @param account The address of the account to query.
     * @return A `ClaimPreview` struct containing details of the claimable yield.
     */
    function getClaimPreview(address account) external view returns (IYieldStreamerTypes.ClaimPreview memory);

2. The ClaimPreview has been extended by adding Exact and Rounded groups of fields:

    /**
     * @dev Structure representing a preview of the claimable yield for an account.
     * Used to estimate the yield that can be claimed without modifying the contract state.
     *
     * Fields:
     * - `yieldExact`: The total claimable yield amount available for the account (without rounding).
     * - `feeExact`: The fee amount that would be deducted during the claim (without rounding).
     * - `yieldRounded`: The total claimable yield amount available for the account (rounded).
     * - `feeRounded`: The fee amount that would be deducted during the claim (rounded).
     * - `timestamp`: The timestamp at which the preview was calculated.
     * - `balance`: The account's token balance used in the calculation.
     * - `rates`: The current yield rates applicable to the account.
     * - `caps`: The current rate caps applicable to the account.
     */
    struct ClaimPreview {
        uint256 yieldExact;
        uint256 feeExact;
        uint256 yieldRounded;
        uint256 feeRounded;
        uint256 timestamp;
        uint256 balance;
        uint256[] rates;
        uint256[] caps;
    }

Contract version

The contract version was updated from v2.1.0 to 2.2.0.

Test coverage

The changes are fully covered by the tests.