Migrate existing plugins to use POJO configuration classes.

[dlvenable]

All plugins should configure the pluginConfigurationType attribute in @DataPrepperPlugin with a custom POJO configuration class. Some older plugins still use PluginSettings. These should be updated to use a POJO configuration class.

For example, the s3 source does this correctly.

data-prepper/data-prepper-plugins/s3-source/src/main/java/org/opensearch/dataprepper/plugins/source/s3/S3Source.java

Line 36 in f6a06a0

@DataPrepperPlugin(name = "s3", pluginType = Source.class, pluginConfigurationType = S3SourceConfig.class)

The opensearch sink is doing this using PluginSettings which we do not want.

data-prepper/data-prepper-plugins/opensearch/src/main/java/org/opensearch/dataprepper/plugins/sink/opensearch/OpenSearchSink.java

Line 89 in 1ddebf6

@DataPrepperPlugin(name = "opensearch", pluginType = Sink.class)

• Update the OpenSearch sink to use a POJO configuration class.
• Look for any other plugins that use the PluginSettings.

[Galactus22625]

I can do