Previously, PropertiesConfigurationFactory would only create a
DefaultPropertyNamePatternsMatcher that ignored case if it was
ignoring unknown fields. If the binding had a target name and
unknown fields were not being ignored the matcher would consider the
case when finding matches. This meant that SERVER_PORT would not being
to ServerProperties.port as SERVER did not match the target name,
server.

This commit updates PropertiesConfigurationFactory to use a
case-ignoring DefaultPropertyNamePatternsMatcher when binding with
a target name. The tests have also been updated to test binding both
with and without ignoring case and using either Properties or
PropertySources. The above-described matching is only performed
against PropertySources and the bug only occurred when using a target
name, making it important to test all combinations.

Closes gh-3745