Document and validate object_type

[jsoriano]

Document and validate the accepted values for object_type and object_type_mapping_type.

Adding the list of accepted values could be a breaking change, but this is not heavily used, and when used, it is only with a reduced subset of the values accepted in this PR. I could apply this only for 2.0.0 if this is a concern.

Implemented in Kibana in elastic/kibana#137772.

Reference to the use in the array type removed because of #412.

Fixes #415
Fixes #416

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• Start Time: 2022-09-14T08:57:01.938+0000

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[mrodm]

LGTM

As you mentioned, as the current packages are already using a subset of the values defined here, I think we can release it before 2.0.0