Proposed Cleanup items for BeanPropertyIntrospector

[Shounaks]

A small effort to reduce complexity.

P.S. sorry for formatting, 😂

Reasoning: BeanPropertyIntrospector is the brain of this library, and it does too much with too little documentation :

1. It does not save the state,
2. It has only 2 methods getting used, while other are helper methods, so only those 2 should be exposed as static
3. this class is self sufficient. i.e. it does not rely on other class or has to generate new object every time it will get used.

Pending Items

• [x] test cases passed
• [x] adding javadocs for methods