Allow groups to be used with standard locations so that order of
profile-specific files is consistent.

Prior to this commit, the default search locations considered for
application properties/yaml files was the following:

	optional:classpath:/
	optional:classpath:/config/
	optional:file:./
	optional:file:./config/
	optional:file:./config/*/

Each of these locations was independent which could cause confusion
if certain combinations were used. For example, if profile-specific
files were added to `classpath:/` and `classpath:/config/` then the
latter would always override the former regardless of the profile
ordering.

This commit updates `StandardConfigDataLocationResolver` so that a
group of locations can be specified for each item. This allows us to
define the following set of search locations which provide more logical
ordering for profile-specific files

	optional:classpath:/;optional:classpath:/config/
	optional:file:./;optional:file:./config/;optional:file:./config/*/

Closes gh-26593