Recursive CTEs: Stage 1 - add config flag

[matthewgapp]

This PR is the first step in a series of PRs to fully implement recursive CTEs in DF. This PR adds a config flag that will be used to gate further implementation of recursive CTE logical and execution plans

Which issue does this PR close?

Working toward closing #462

Rationale for this change

What changes are included in this PR?

Are these changes tested?

Are there any user-facing changes?

[alamb]

Thanks @matthewgapp -- what would you think about filing a ticket with the implementation plan described in #7581 (comment) (or maybe we can put it on #462 itself)?

[alamb]

I think some tests need updating to get the CI run clean here

[matthewgapp]

I think some tests need updating to get the CI run clean here

Yeah, this is still a draft, so not quite ready for CI. I'm going to be readying these PRs this afternoon and will mark them Ready for review when done.

[matthewgapp]

I think some tests need updating to get the CI run clean here

Yeah, this is still a draft, so not quite ready for CI. I'm going to be readying these PRs this afternoon and will mark them Ready for review when done.

Spent most of my time today digging into the repro and solution to the bug(s) we're seeing downstream. Hope to finish that and then clean up these PRs this weekend.

[matthewgapp]

I think some tests need updating to get the CI run clean here

Yeah, this is still a draft, so not quite ready for CI. I'm going to be readying these PRs this afternoon and will mark them Ready for review when done.

Spent most of my time today digging into the repro and solution to the bug(s) we're seeing downstream. Hope to finish that and then clean up these PRs this weekend.

Thinking that I'll have these three PRs ready for review sometime tomorrow afternoon.

[matthewgapp]

Thinking that I'll have these three PRs ready for review sometime tomorrow afternoon.

Think it's ready for review :)

[alamb]

Thank you @matthewgapp