analysis-common: make UniqueTokenFilter public

this way the filter can also be used from plugins which implement
analyzers and want to use it.
the current workaround is that the plugin has to implement the usage
from it in a package with the same name, which is just an ugly hack.

Signed-off-by: Ralph Ursprung <[email protected]>

modules/analysis-common/src/main/java/org/opensearch/analysis/common/UniqueTokenFilter.java

@@ -44,7 +44,7 @@
  * A token filter that generates unique tokens. Can remove unique tokens only on the same
  * position increments as well.
  */
-class UniqueTokenFilter extends TokenFilter {
+public class UniqueTokenFilter extends TokenFilter {
 
     private final CharTermAttribute termAttribute = addAttribute(CharTermAttribute.class);
     private final PositionIncrementAttribute posIncAttribute = addAttribute(PositionIncrementAttribute.class);