Check if IC has serializable_keys? and transform them, this saves
some computing since we don not have to use :use_ar_object just
because the model has: serialize <col_name>

Add TODOs for noticed possible bugs

Use to_sym for individual keys instead of symbolize_keys!

Performance tweaks for the base saver, getting repeated logic
computed in initializer. Getting record_key abrtratcion for
fetching attributes of non AR records.

Perf tweaks of the batch saver:
1. Having iterator that fetches raw SQL without creationg AR
   objects.
2. Select on the fetched data to reduce the mem size needed.
3. Bumping batch_size to 10k, since the objects are 10x smaller
   than AR objects.
And few small tweaks in the core saving

Perf tweaks in SQL mixin:
1. Store connection for the whole batch
2. Precalculate pg_types for faster type_casting

Fix bad comments

Fix rubocop issues

Correct symbol vs string keys

Move batch size to attributes with setter, so we avoid computing
it multiple times.

Remove redundant symbolize_keys

Use faster inventory_object.id call

Store primary_key_value to avoid multiple method calls

Use reorder for find_in_batches working properly