Primitive Key Epic

[big-andy-coates]

This issue tracks remaining work for extending KSQL's support of key types beyond just STRING to other primitive key types.

Subtasks:

• Support INT, BIGINT, DOUBLE and STRING
• Support DECIMAL keys
• allow key names other than ROWKEY
• Deprecate WITH(KEY='z')

Optional:

• Consider supporting PRIMARY KEY syntax on tables vs KEY syntax on streams.
• LogicalSchema should also include WindowType

[big-andy-coates]

Replaced by: https://github.com/confluentinc/ksql/projects/3