Simple Utility Functions

Multiple Simple Utility Functions:

- String Functions: Uppercase, Lowercase, Reverse, Count, etc.
- Math Functions: Percentage, Average, Fraction, Simple Calculator.
- Date Functions: Stopwatch, Timer, Find Age, Calculate difference between 2 Dates, Check if Leap Year.
- Unit Conversions: Simple conversions between units.
- Developer Tools: Simple XML and JSON Validation.