Summary
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Emit a warning for removal message if `COMPAT` is specified with `java.locale.providers` system property

Problem
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`COMPAT` locale provider has remained to keep the backward compatibility of JDK 8's locale data, since CLDR-based locale data became the default in JDK 9. The intention was to encourage applications to migrate to CLDR, so for future removal of the `COMPAT` locale provider, acknowledging the user of future removal is recommended.

Solution
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If `COMPAT` and/or `JRE` is specified in the command line option of `java.locale.providers` system property, print a message warning the user of future removal. Also, replace the wording of the defunct "Java Runtime Environment" with "JDK Reference Implementation."

Specification
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Modify the class description of `java.util.spi.LocaleServiceProvider` class as follows:

    @@ -118,22 +118,23 @@
       * the locale sensitive services separated by a comma. As this property value is
       * read and cached only at the initialization of this class, users should specify the
       * property on the java launcher command line. Setting it at runtime with
       * {@link System#setProperty(String, String)} is discouraged and it may not affect
       * the order.
    -  * <p>
    -  * Java Runtime Environment provides the following four locale providers:
    +  * JDK Reference Implementation provides the following four
    +  * locale providers:
       * <ul>
       * <li> "CLDR": A provider based on Unicode Consortium's
       * <a href="http://cldr.unicode.org/">CLDR Project</a>.
       * <li> "COMPAT": represents the locale sensitive services that is compatible
    -  * with the prior JDK releases up to JDK8 (same as JDK8's "JRE").
    +  * with the prior JDK releases up to JDK 8 (same as JDK 8's "JRE"). This
    +  * provider is deprecated and will be removed in the future release of JDK.
       * <li> "SPI": represents the locale sensitive services implementing the subclasses of
       * this {@code LocaleServiceProvider} class.
       * <li> "HOST": A provider that reflects the user's custom settings in the
       * underlying operating system. This provider may not be available, depending
    -  * on the Java Runtime Environment implementation.
    +  * on the JDK Reference Implementation.
       * <li> "JRE": represents a synonym to "COMPAT". This name
       * is deprecated and will be removed in the future release of JDK.
       * </ul>
       * <p>
       * For example, if the following is specified in the property: