changefeedccl: elide SELECT * in changefeed expressions

[shermanCRL]

In changefeed expressions, a basic expression may look like:

CREATE CHANGEFEED INTO 'kafka://server'
AS SELECT * FROM foo
WHERE x > 2

It occurs to me that we can elide the SELECT * in the above example.

CREATE CHANGEFEED INTO 'kafka://server'
FOR foo    [or maybe FOR TABLE foo]
WHERE x > 2

I find this easier to read and write -- especially for a new user. If you simply want a filter, the expression is simple. [adage]

The existing syntax is clear, explicit and well-defined. My suggestion here is sugar, a reduction in verbosity. It’s analogous to eliding types by type inference.

Jira issue: CRDB-17654

Epic CRDB-21713

[blathers-crl[bot]]

cc @cockroachdb/cdc

[amruss]

Notes: We should be explicit about the syntax we want before launching