Adds `quickcheck` property based tests to the recently merged
`generate_series` implementation and fixes various issues in it:
- `0` for `step` should be treated as `1`
- missing `step` should be treated as `1`
- a string like `a` for `step` should be treated as `1`
- saturating overflow
- return an empty series for a variety of invalid inputs, instead of
erroring
For the future:
We should have e2e/fuzz tests comparing sqlite implementation to limbo
implementation
Reviewed-by: Preston Thorpe (@PThorpe92)
Closes#910