sql/inspect: add INSPECT support for indexes on virtual columns

Currently, we are unable to validate consistency of any index that has keys over virtual columns. Internally, INSPECT will run a `LEFT LOOKUP JOIN ... FORCE_INDEX`. And this fails if the keys included in the join are for virtual columns. The plan fails with an error like:
```
could not produce a query plan conforming to the LOOKUP JOIN hint
```

These types of indexes are blocked. This issue is opened to remove the block and allow them to be inspected. The thinking is that we can do a merge join instead of a lookup join. But this requires more investigation.

Before the block, you could hit an error during INSPECT with this set of commands:
```
CREATE TABLE t1 (
c1 INT,
c2 INT AS (c1 + 1) VIRTUAL,
INDEX (c2)
);
-- CREATE TABLE

INSERT INTO t1 VALUES (1);
-- INSERT 0 1

SET enable_inspect_command = true;

INSPECT TABLE t1;
-- ERROR: INSPECT found inconsistencies
-- SQLSTATE: 22000
```

Jira issue: CRDB-55650

Epic CRDB-55075