[PROPOSAL] Move OpenSearch.Client Request/Descriptor classes into namespaces

[Xtansia]

What/Why

What are you proposing?

Currently the RequestParameter types in OpenSearch.Net are in specific namespaces such as OpenSearch.Net.Specification.SnapshotApi, however in OpenSearch.Client all Request and Descriptor types are directly placed in the OpenSearch.Client namespace. This is prone to collisions in naming as some have very generic names such as RestoreRequest which will collide with remote store's restore operation. As such I propose moving the Request/Descriptor classes in OpenSearch.Client into matching respective namespaces as is done in OpenSearch.Net.

What users have asked for this feature?

• Me 😄 (as part of my investigation into [FEATURE] Generate API code from OpenSearch API Spec #193)

What problems are you trying to solve?

Collisions of type names due to placing all requests into the same namespace.

Are there any security considerations?

No

What is the user experience going to be?

User experience is unchanged other than needing to add new usings for specific namespaces.

Are there breaking changes to the User Experience?

Yes, namespaces will change, as such users will have to update their usings, otherwise API remains identical.

Why should it be built? Any reason not to?

• Unifies namespace layout between OpenSearch.Net and OpenSearch.Client
• Reduces chances of type name collisions, and is less invasive than renaming the types or ambiguously appending a number etc.
• It's a breaking change and will require a major version bump

What will it take to execute?

Reasonably low-effort changing namespaces of all request and descriptor types.