Polish static resource handling mechanism

- ResourceResolver and ResourceResolverChain now have a consistent API
  with regard to method names and terminology.

- ResourceResolver and ResourceResolverChain now accept
  List<? extends Resource> instead of List<Resource> for simplified
  programmatic use.

- Improved Javadoc across the package.

- Formatted code to align with standards.

- Removed all references to ResourceUrlPathTranslator.

Issue: SPR-10933