Deprecate tokenize parameter in field definition

[aprudhomme]

These are some proposed changes for the 1.0.0-SNAPSHOT branch around the handling of tokenization of text based fields.

• The tokenize parameter in the field definition is deprecated and no longer used
• TEXT type fields will always be tokenized
• ATOM type fields will never be tokenized
• ATOM norms are alway omitted, this is the default in ES. Ideally, we would want to make this configurable, but the grpc type does not allow for detecting when this is unset (and TEXT fields need the opposite default). Since this is not a commonly used option, I think hard coding the value is ok for now.
• ATOM fields are no longer indexed for search when the search property is false

Additionally

• references to the tokenize parameter have been removed
• the parameter has been removed from schema files
• the search parameter has been added to ATOM fields storing doc_id values in schemas, as they are no longer searchable without it. It would be good to switch these to _ID fields at some point, but that is beyond the scope of this branch.

[aprudhomme]

The example plugin test is an expected failure, since it builds against the latest published version