Correctly throw exception on attempt to parse invalid Date

[alexey-milovidov]

Changelog category (leave one):

• Improvement

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):
Correctly throw exception on attempt to parse invalid Date. This closes #6481.

[alexey-milovidov]

Let's look at the performance test.
Also need to check for possible performance regressions manually.

[alexey-milovidov]

SELECT count() FROM system.numbers WHERE NOT ignore(toDate(toString(toDate(toUInt16(number)))))

This PR: 410.24 MB/s.
master: 405.34 MB/s.

[alexey-milovidov]

SELECT count() FROM system.numbers WHERE NOT ignore(toDate(materialize('2020-01-01')))

This PR: 678.09 MB/s.
master: 655.49 MB/s.

[alexey-milovidov]

Performance test is Ok. I'm surprised.