perf: have syscall/datastore insert method avoid converting the BSATN-encoded row to PV

[Centril]

Depends on #2013.

Deal with the BSATN directly, inserting it into the table, avoiding the PV.

Indices will still need AVs, but will be projected from the BFLATN.

[cloutiertyler]

https://discord.com/channels/931210784011321394/1150256030433955870/1311406963208359996

Discussion regarding whether it's actually prereq. TL;DR we're going to add a new insert_bsatn function in write_row_to_pages_bsatn and then remove the insert function in a separate PR while updating the merge function in that PR as well.