[tech debt]: Remove detoasting from the compression algorithms as the caller already does this

[dbeck]

What type of enhancement is this?

Refactor

What subsystems and features will be improved?

Compression

What does the enhancement do?

As @akuzm pointed out in the review of #7701 , the detoasting is not necessary for bool compression. Because this works the same way for all compression algorithms I don't want to add this change to the mentioned PR, but rather raise a change the consistently addresses the issue across all compression algorithms.

Remove PG_DETOAST_DATUM from ${ALGO}decompression_iterator_from_datum${DIRECTION} and add an assert instead, to make sure it does receive a detoasted Datum.

Implementation challenges