RBWNAT inserts are broken with EPHEMERAL and MATERIALIZED columns

[slvrtrn]

This will break inserts that leave out columns with default values, and relatedly, it will make it impossible to insert into tables with MATERIALIZED or ALIAS columns altogether. Perhaps this function should use the DESCRIBE TABLE output rather than the RowBinaryWithNamesAndTypes header?

Originally posted by @timvermeulen in #244 (comment)

[slvrtrn]

Also check EPHEMERAL https://clickhouse.com/docs/sql-reference/statements/create/table#ephemeral

[slvrtrn]

@slvrtrn to prepare a branch with the tests demonstrating the failures.

[slvrtrn]

Ephemeral is broken with validation: e25db98

Perhaps we can use a select from system columns instead:

SELECT
    name,
    type,
    position,
    default_kind,
    default_expression
FROM system.columns
WHERE (`table` = 'test') AND (database = 'default')
ORDER BY position ASC

   ┌─name────┬─type───────────┬─position─┬─default_kind─┬─default_expression───────────────┐
1. │ id      │ UInt64         │        1 │              │                                  │
2. │ unhexed │ String         │        2 │ EPHEMERAL    │ defaultValueOfTypeName('String') │
3. │ hexed   │ FixedString(4) │        3 │ DEFAULT      │ unhex(unhexed)                   │
   └─────────┴────────────────┴──────────┴──────────────┴──────────────────────────────────┘

There should not be any issues with grants, cause if you have access to a table, you automatically get access to its related system.columns view rows.

[slvrtrn]

ALIAS works fine.
MATERIALIZED is broken, see 1cb1834