This adds an `include_type_name` option to the `indices.create`,
`indices.get_mapping` and `indices.put_mapping` APIs, which defaults to `true`.
When set to `false`, then mappings will be returned directly in the body of
the `indices.get_mapping` API, without keying them by the type name, the
`indices.create` will expect mappings directly under the `mappings` key, and
the `indices.put_mapping` will use `_doc` as a type name and fail if a `type`
is provided explicitly.

On 5.x indices, get-mapping will fail if the index has multiple mappings, and
put-mapping will update or introduce mappings for the `_doc` type instead of
updating existing mappings. This oddity is required so that we don't have to
introduce a new flag to put-mapping requests to know whether they are actually
updating the `_doc` type or performing a typeless call.

Relates elastic#15613

This adds an `include_type_name` option to the `indices.create`,
`indices.get_mapping` and `indices.put_mapping` APIs, which defaults to `true`.
When set to `false`, then mappings will be returned directly in the body of
the `indices.get_mapping` API, without keying them by the type name, the
`indices.create` will expect mappings directly under the `mappings` key, and
the `indices.put_mapping` will use `_doc` as a type name and fail if a `type`
is provided explicitly.

On 5.x indices, get-mapping will fail if the index has multiple mappings, and
put-mapping will update or introduce mappings for the `_doc` type instead of
updating existing mappings. This oddity is required so that we don't have to
introduce a new flag to put-mapping requests to know whether they are actually
updating the `_doc` type or performing a typeless call.

Relates #15613

From #29453 and #37285, the `include_type_name` parameter was already present and defaulted to false. This PR makes the following updates:
- Add deprecation warnings to `RestPutMappingAction`, plus tests in `RestPutMappingActionTests`.
- Add a typeless 'put mappings' method to the Java HLRC, and deprecate the old typed version. To do this cleanly, I opted to create a new `PutMappingRequest` object that differs from the existing server one.

From #29453 and #37285, the include_type_name parameter was already present and defaulted to false. This PR makes the following updates:
* Add deprecation warnings to RestCreateIndexAction, plus tests in RestCreateIndexActionTests.
* Add a typeless 'create index' method to the Java HLRC, and deprecate the old typed version. To do this cleanly, I created new CreateIndexRequest and CreateIndexResponse objects that differ from the existing server ones.

From #29453 and #37285, the include_type_name parameter was already present and defaulted to false. This PR makes the following updates:
* Add deprecation warnings to RestCreateIndexAction, plus tests in RestCreateIndexActionTests.
* Add a typeless 'create index' method to the Java HLRC, and deprecate the old typed version. To do this cleanly, I created new CreateIndexRequest and CreateIndexResponse objects that differ from the existing server ones.