Add method to get a token within the same scope as the $stackPtr (before/after)

[jrfnl]

Sort of a scoped version of the File::getNext()/File::getPrevious() methods.

Method should take the following parameters: File $phpcsFile, int $stackPtr, $skipFn = true

The method should automatically limit searches to its own scope, i.e. the function/method it is in or the global scope.

The method should skip over:

• All nested closed construct declarations (function/closure/class etc)
• Optionally skip over (open scope) arrow function declarations.

Typical use cases:

• Finding an assignment to a variable within the current scope.
• Finding the use of a function within the current scope.
• etc