UnicodeData Unit Tests

### Description 

Add test coverage for [UnicodeData](https://github.com/devstein/unicode-eth/blob/main/contracts/UnicodeData.sol) in [UnicodeData.test.ts](https://github.com/devstein/unicode-eth/blob/main/test/UnicodeData.test.ts#L111-L141).

These tests are meant to test the UnicodeData contract API but are not meant to be integration tests for the Unicode Character Database initialization. 