Add useAlwaysMessageFormat configuration key

Allow to configure the `useAlwaysMessageFormat` attribute of
`MessageSource` via configuration.

Closes gh-5483

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

@@ -113,6 +113,7 @@ content into your application; rather pick only the properties that you need.
 	spring.messages.cache-seconds=-1 # Loaded resource bundle files cache expiration, in seconds. When set to -1, bundles are cached forever.
 	spring.messages.encoding=UTF-8 # Message bundles encoding.
 	spring.messages.fallback-to-system-locale=true # Set whether to fall back to the system Locale if no files for a specific Locale have been found.
+    spring.messages.always-use-message-format=false # Set whether to always apply the MessageFormat rules, parsing even messages without arguments.
 
 	# OUTPUT
 	spring.output.ansi.enabled=detect # Configure the ANSI output (can be "detect", "always", "never").