aces#9334)

This adds `\LORIS\Database\Query` class which is both an iterator an
countable to replace the return value of `Database->pselect()`. This
improves the memory consumption of large datasets, because the iterator
only needs to load the row that is being foreach'd over, instead of
loading the entire query result into memory.

Places that currently depend on it being an array are wrapped in
`iterator_to_array` (They are mostly queries returning small results, so
this isn't expensive. The optimization is mostly useful for places like
the dataquery module which iterate over large amounts of data.)

aces#9334)

This adds `\LORIS\Database\Query` class which is both an iterator an
countable to replace the return value of `Database->pselect()`. This
improves the memory consumption of large datasets, because the iterator
only needs to load the row that is being foreach'd over, instead of
loading the entire query result into memory.

Places that currently depend on it being an array are wrapped in
`iterator_to_array` (They are mostly queries returning small results, so
this isn't expensive. The optimization is mostly useful for places like
the dataquery module which iterate over large amounts of data.)

This updates DBRowProvisioner to remove the strval (and fixes #9335).

After doing that, it became clear that the inner class could be replaced
by a generator while still fulfilling the contract of returning a
`\Traversable`. Doing this made it more obvious that since #9334,
pselect could be used directly while maintaining the lazy evaluation
instead of bypassing the Database object to use the PDO directly.
However this required injecting a `LorisInstance` object to the
constructor to get the database connection.

With access to the `LorisInstance` object, the `DBRowProvisioner` can
also get a new database connection and disable query buffering to lazily
retrieve rows since PR #9344. This may theoretically improve performance
and memory usage on large provisioners but has not been tested.
(Performance did not decrease in raisinbread but it is not a large
dataset where it would be noticeable.)

This wraps the $db->pselect() call with iterator_to_array so that it can be processed with .map in DiagnosisEvolution.js. This is necessary following the change in #9334

    Resolves #9711