Enhance HandlerMappingIntrospector to cache parsed patterns

[rstoyanchev]

#24945 added support for parsed PathPatterns but in order to integrate with this Spring Security has to parse its patterns in one of several ways depending on how many differently configured PathPatternParser's are in use (see spring-projects/spring-security#8691).

This ticket is to try and encapsulate the parsing and caching of patterns so that Spring Security does not need to be aware of those details and continue to use the same API passing String patterns as input. Internally Spring MVC would have to then to parse patterns lazily and build up the cache.