Perform refactoring of AnnotationLocationCheck to increase code readability

[MEZk]

Points to improve:

1. Many methods of AnnotationLocationCheck class have copy-pasted javadoc.
   For example,

   checkstyle/src/main/java/com/puppycrawl/tools/checkstyle/checks/annotation/AnnotationLocationCheck.java

   Line 275 in b4a337a

   private static boolean hasAnnotations(DetailAST modifierNode) {

   ,

   checkstyle/src/main/java/com/puppycrawl/tools/checkstyle/checks/annotation/AnnotationLocationCheck.java

   Line 284 in b4a337a

   private static int getAnnotationLevel(DetailAST modifierNode) {

   , and others.
2. Method names are not clear enough to understand their purposes without diving inside. For example,
   what does getAnnotationLevel mean? Does the annotation have the level? Does the level refer to a language structure?
3. Some variables and method parameters have unclear names too. For example, what does the parameter name correctLevel mean? Javadoc also says nothing.

Points 1-3 need to be improved.

[romani]

fix is merged.