Add security.basic.authorize-mode property

Add a `security.basic.authorize-mode` property that can be used to
affect how basic security authorization is applied.

Fixes gh-2462

spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -211,6 +211,7 @@ content into your application; rather pick only the properties that you need.
 	security.basic.enabled=true
 	security.basic.realm=Spring
 	security.basic.path= # /**
+	security.basic.authorize-mode= # ROLE, AUTHENTICATED, NONE
 	security.filter-order=0
 	security.headers.xss=false
 	security.headers.cache=false