Add support for CROSS APPLY and OUTER APPLY generation

[niekschoemaker]

Shamelessly copied from the postgres sql provider, that's why I added the copyright notice above it, no need to reinvent the wheel as they already solved it.

Implement VisitCrossApply and VisitOuterApply methods to translate CROSS APPLY and OUTER APPLY constructs for Firebird using lateral joins. Adapted logic from Npgsql EF Core provider.

Related to issue #1165

[cincuranet]

There's a lot of tests that result in CROSS APPLY/OUTER APPLY that are ignored now, these need to be enabled. You can start by searching for NotSupportedOnFirebirdFact/NotSupportedOnFirebirdTheory.

[niekschoemaker]

There's a lot of tests that result in CROSS APPLY/OUTER APPLY that are ignored now, these need to be enabled. You can start by searching for NotSupportedOnFirebirdFact/NotSupportedOnFirebirdTheory.

Just making sure, I'm going through all disabled tests at the moment, and if I spot things which are marked as unsupported by efcore, but which are supported now, should those be enabled too?

[cincuranet]

if I spot things which are marked as unsupported by efcore, but which are supported now, should those be enabled too?

Yes. But create separate PR.

[niekschoemaker]

Alright, sorry about the mess with force pushes, I completely overlooked the Firebird 3 and 4 support so naively tested on firebird 5 and enabled way too many tests.
Commits look clean and on the fork the tests passed so should be good now!