feat: support sqlite

[rasviitanen]

Adds support for sqlite.

closes: #161

Todo

• A test harness - we should proabably create a test harness at synth/testing_harness/sqlite. But here we don't have to run docker, so question is if we want something else?
• The random sampling does not work as intended as sqlite's random doesn't support a seed.
• I would like to add some tests for fetching column names etc from sqlite to make sure they work as intended. But I was not sure how you want to structure these tests. Maybe it's sufficient witht he test harness.

Other

• I had some issues when generating to an empty directory, so I added support for this [commit !85ca11b]
• I had some issues where I had low=Bound::Included(1) and high=Bound::Excluded(1). To me it feels natural that this range includes a number 1, so I added some code for this [commit !8ba84fa]. It also includes the number if you have low=Bound::Excluded(1) and high=Bound::Included(1), I am not equally sure about this case though.

I can drop these two commits if they are not desired.

[rasviitanen]

@christoshadjiaslanis please take a look. If you want to take it over it's fine by me 😃
Otherwise I'll take a look at the remaining things and feedback next time I get some time over.

[christos-h]

@rasviitanen thank you for this it looks great! I'll happily take it over the line from here.

I think the deterministic sampling is a prerequisite for the testing harness (if we stick to the golden master strategy we have for other datasources).

Regarding the bounds - I think they're breaking some tests. I'm not sure I understand why this felt unnatural - perhaps you could elaborate?

Regarding generating into an empty directory - I think that's a great idea so thank you!

[rasviitanen]

@christoshadjiaslanis Thanks!

I guess the bounds issue originates from synth generating an empty bounds set (Included(x), Excluded(x)) if I only have a single item in the table I am importing from. With this, the generation returns an error as the range is empty. Maybe the issue is that synth generates an empty range in this case instead of some constant. (Included(x), Excluded(x)) should indeed be an empty range, so idk what I was thinking when changing this. Should have looked at the root cause instead.

[hbina]

This should be a separate PR.