RateLimiter: new view functions + their test coverage

[ChiTimesChi]

Description

Added a bunch of new view functions for RateLimiter, updated the tests to cover them.

function getTransactionAt(uint256 index)
    external
    view
    returns (
        bytes32 key,
        bytes memory payload,
        uint32 storedAtMin
    );

function getTransactionByKappa(bytes32 kappa)
    external
    view
    returns (bytes memory payload, uint32 storedAtMin);

function getUnhandledKappas()
    external
    view
    returns (bytes32[] memory kappas);

function unhandledKappasCount() external view returns (uint256 kappaCount);

Checklist

• New Contracts have been tested
• Lint has been run
• I have checked my code and corrected any misspellings

[coveralls]

Pull Request Test Coverage Report for Build 2327972853

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 20 (0.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.7%) to 51.578%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
contracts/bridge/RateLimiter.sol	0	20	0.0%

Totals
Change from base Build 2310283189:	-0.7%
Covered Lines:	803
Relevant Lines:	1479

---

💛 - Coveralls

[trajan0x]

Needs coverage for:

• getTransactionByKappa
• getTransactionAt