pgsql: aio: Regularize IO worker internal naming.

aio: Regularize IO worker internal naming. Adopt PgAioXXX convention for pgaio module type names. Rename a function that didn't use a pgaio_worker_ submodule prefix. Rename the internal submit function's arguments to match the indirectly relevant function pointer declaration and nearby examples.

pgsql: aio: Regularize IO worker internal naming.

aio: Regularize IO worker internal naming. Adopt PgAioXXX convention for pgaio module type names. Rename a function that didn't use a pgaio_worker_ submodule prefix. Rename the internal submit function's arguments to match the indirectly relevant function pointer declaration and nearby examples.