[Extensions]Versioning support for plugin extension points

[saratvemulapalli]

Plugins are rigid in terms of compatibility and have to be built with a specific x.y.z version of OpenSearch during compile time. This tight coupling reduces the velocity of software development lifecycle for OpenSearch and plugins because it requires all plug-ins to release at the same time when a version number is raised.

Ref: #1707

The underlying problem is lack of versioning support for extension points (https://opensearch.org/blog/technical-post/2021/12/plugins-intro/) on which plugins are extended.

We would like to see OpenSearch being compatible with different versions of plugins/extensions.
This would need modularization of opensearch starting with all the extension points.

• Versioning support for all extension points.
• Versioning support for underlying core modules (like Settings etc).
• Build and publish versioned SPI's for plugin/extension developers.
• Add support to register/remove extension point handlers dynamically.

Ref: Extension Points:

getFeature - Implement a custom feature and respond to cluster state API.
createModules - Implement node level dependency injection modules via Guice.
getGuiceServiceClasses - Node level services which will be automatically called with node state changes.
createComponents - Custom component implemented and its lifecycle being managed by OpenSearch.
additionalSettings - Implement additional node level settings.
getNamedWriteables - Custom parsers the plugin would use for transport messaging.
getNamedXContent - Custom parsers the plugin would use for NamedObjects.
onIndexModule - Index level extension point, called before an index is created.
getSettings - Implement additional cluster level settings.
getSettingsFilter - Implement additional cluster level settings filter.
getSettingUpgraders - Implement setting upgraders.
getIndexTemplateMetadataUpgrader - An extension to modify index template metadata on startup.
getExecutorBuilders - Implement custom thread pools for executions.
getBootstrapChecks - Add additional bootstrap checks when OpenSearch node initializes.
getRoles - Implement additional DiscoveryNodeRole’s.
getAdditionalIndexSettingProviders - Implement additional index level settings for newly created indices.