Expose connect_options for initialized pools and database on the PgConnectOptions

[Nukesor]

This is a PoC PR which is related to #1853

The idea is to expose PoolOptions and ConnectionOptions after the pool has been created.

This would allow easy database deletion and modification without having to save the options used during creation for the whole duration of the program.

[Nukesor]

@abonander Sorry for the quite sloppy first state of the MR, I should have properly tested it in a fully integrated scenario from the very beginning.

[svenstaro]

@Nukesor might want to update the PR name and commit title to reflect the new actual changes.

[abonander]

I don't think this implementation fixes #1853 as they specifically wanted PoolOptions.

[Nukesor]

True. @Thomasdezeeuww should then easily be able to implement theire desired getters in a follow-up PR.

I didn't want to expose the getter without adding specific getters, but I guess it makes sense :)

Thanks @abonander for the review 👍

[svenstaro]

@abonander For the record, even if it doesn't fix the original issue it meant to address, it's still very helpful for a case I have right now and would therefore appreciate to see it merged. :)

@Nukesor you should remove the issue from the OP so it doesn't auto close upon merging.

[Nukesor]

I changed it from fixes to is related to