Add page size limit

[pulpn0ir]

Allows setting a page size limit when creating a DatabaseContext to prevent server overloads.

If the requested page size exceeds the limit, the response page is capped to the defined limit. The default value is nil, allowing for an unlimited page size.

This PR relates to vapor/fluent#715

[siemensikkema]

This PR is the continuation of #406

[Joannis]

@0xTim any reason this wasn't merged (yet)?

[0xTim]

@siemensikkema I was waiting for you to give the final OK for this, this good to merge? Don't merge just yet if so, just approve. I'll be sorting out the release bot in a couple of hours so we can wait for that

[Joannis]

After a small discussion with @0xTim it seems he wants at least @gwynne or @siemensikkema to look into this as well.

[gwynne]

Looks mostly fine to me, but I'd like the unit tests to include a test for a page other than the first (in particular, a test that pages after the first are at the correct offset relative to the given limits).

[siemensikkema]

@gwynne good idea. I changed the test slightly to ensure this is covered. I chose to reduce the page limit so I could request page 2 while still getting a full page. The other choice I could have made would have been to add one more row to the test output.

accepted as per discussion on Discord

[VaporBot]

These changes are now available in 1.12.0