Expand static resource handling mechanism

An initial commit with expanded support for static resource handling:

- Add ResourceResolver strategy for resolving a request to a Resource
  along with a few implementations.

- Add PublicResourceUrlProvider to get URLs for client-side use.

- Add ResourceUrlEncodingFilter and
  PublicResourceUrlProviderExposingInterceptor along with initial
  MVC Java config support.

Issue: SPR-10933

spring-webmvc/src/test/resources/org/springframework/web/servlet/resource/test/bar.min.css

@@ -0,0 +1 @@
+h2 { color:white; }

spring-webmvc/src/test/resources/org/springframework/web/servlet/resource/test/foo-bar/foo-bar.css

@@ -0,0 +1 @@
+h2 { color:white; }

spring-webmvc/src/test/resources/org/springframework/web/servlet/resource/test/foo-e36d2e05253c6c7085a91522ce43a0b4.css

@@ -0,0 +1 @@
+h1 { color:red; }

spring-webmvc/src/test/resources/org/springframework/web/servlet/resource/test/foo.css.less

@@ -0,0 +1 @@
+h1 { color:red; }

spring-webmvc/src/test/resources/org/springframework/web/servlet/resource/test/zoo.css.less

@@ -0,0 +1 @@
+h1 { color:red; }