Move methods common in UnusedLocalVariableCheck and FinalClassCheck to util

[Vyom-Yadav]

From #10930 (comment)
To be addressed after merging #10930
UnusedLocalVariableCheck (#10930) and FinalClassCheck (Check + #10968) has some methods in common-

- extractQualifiedName(..)
- classNameMatchingCount(..)
- getQualifiedClassOrInterfaceName(DetailAST classAst) (known as `getQualifiedClassName` in final class)
- getQualifiedClassOrInterfaceName(String packageName, String outerClassQualifiedName, String className) (known as `getQualifiedClassName` in final class)

Also FinalClassCheck and UnusedLocalVariableCheck have a static nested class in common - ClassDesc. We may merge both of these classes and extract it somewhere, there are some overlapping properties.

When #10968 will be merged, extract these methods to util and try to remove the suppression for ExcessiveClassLength in UnusedLocalVariableCheck.

[romani]

we need to make sure that after moving to Util classes such methods we will not start covering them by pure unit test. All coverage should be done by Inputs like tests (functional tests).

[Vyom-Yadav]

UT's won't be required.

[Vyom-Yadav]

@nmancus1 @romani I want to combine TypeDeclDesc and ClassDesc and extract them somewhere, what would be the right place to extract them? I am thinking to place it in the util folder, will that be alright?

[romani]

ok, to keep them in 'util' package for now