refactor: refactoring guesses package

[vvatanabe]

• optimized pattern matching in uppercaseVariations and reduced lowercaseToken generation in l33tVariations of DictionaryGuess
• clarified exec logic, removed unnecessary else, and improved readability with early returns in RegexGuess
• replaced switch with map lookup, extracted guess initialization, and reduced nesting with early returns in EstimateGuess
• optimized START_POINTS lookup with Set, cached regex pattern, and improved code readability in SequenceGuess
• split the logic inside the exec method of SpatialGuess into two new private methods
• split the logic inside the exec method of DateGuess into two new private methods
• split the logic inside the exec method of BruteforceGuess into two new private methods
• add brackets to the if statement in BaseGuess