Move Statement and Expr so they hold identifiable structs

[tvallotton]

This is of course a major breaking change. But I think it's worth considering. I also fixed the DROP CONSTRAINT thing I mentioned in #342.

[alamb]

Thank you for the contribution @tvallotton 👍

In general, I don't feel qualified to approve / accept this level of change without some additional buy in from @nickolay / @andygrove / @Dandandan . #311 (comment) seems like a good usecase to me but it is a pretty major change for all users of sqlparser-rs.

I view myself as a caretaker now and feel good about merging and releasing "round out the SQL support" type PRs. Splitting out the changes to ALTER TABLE as a separate PR, for example, would be fine,

[alamb]

this file looks pretty specific to your own environment -- did you mean to propose including it into this PR?

[tvallotton]

Oh yeah I think I was a little careless as I initially didn't think I was going to submit a pull request. I also noticed I made the changes on the master branch, would you prefer I did another submission on a separate branch?

[alamb]

I also noticed I made the changes on the master branch,

I don't think it matters what branch you work on in your fork (tvallotton:main is fine)

[alamb]

this is probably not accurate

[alamb]

See also #311

[alamb]

Closing old seemingly stalled PR. Please re-open if this was a mistake

[alamb]

Sadly I don't have the time to help drive projects such as this. Unless one of the other maintainers wants to do so, PRs like this are not likely to be merged. I am sorry I don't have the time and I am sorry if your time was wasted.

As the current state of affairs might not have been clear in the project's README. I have added #416 to try and help