feat: timestamp inequality support

[Dustin-Ray]

Rationale for this change

Quick PR to add support for inequality expressions between timestamps. Since theyre represented internally as i64, they can be easily compared against one another.

What changes are included in this PR?

Adds support for statements with the following syntax:

SELECT * FROM table WHERE times <= timestamp '1970-01-01T00:00:00Z
SELECT * FROM table WHERE times >= timestamp '1970-01-01T00:00:00Z
SELECT * FROM table WHERE times > timestamp '1970-01-01T00:00:00Z
SELECT * FROM table WHERE times < timestamp '1970-01-01T00:00:00Z

Are these changes tested?

yes

[iajoiner]

Hmm where did you actually compare timestamps? Moreover how do you do it with different timezones?

[Dustin-Ray]

Hmm where did you actually compare timestamps? Moreover how do you do it with different timezones?

I would point you to this test here which is probably the most significant example, this test confirms that our approach matches that of postgres.

I have also added many other examples in this PR which test inequalities on various timezones as you pointed out coverage was lacking in those areas

[iajoiner]

@drcapybara BTW it will be really great if you use git rebase main and squash your commits. Ideally there should either be one commit per PR or the commits should have clear differentiation (e.g. add Bar for one and add Foo for another). If you check out how Linux kernel and Bitcoin community use git you will find out that they use this approach.
@dalbertom

[iajoiner]

Really thanks for submitting and repeatedly modifying this PR! I really appreciate this!

[github-actions]

🎉 This PR is included in version 0.5.8 🎉

The release is available on GitHub release

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