Add support for ignore_missing_conponent_templates in put_index_template

[honzakral]

This parameter is not supported and there is no workaround.

This is another result of the undocumented removal of the body parameter (see elastic/elasticsearch-py#2181) which is making the client unusable for some scenarios.

[pquentin]

This parameter is not supported and there is no workaround.

This issue was transferred from elasticsearch-py, and indeed with the current Python client, one needs to perform a raw request when even a single key is missing from the specification.

[pquentin]

This was fixed by @l-trotta in #2488. Closing, thanks!