[PP-1] Views Date Filter Datetime Granularity Option

The core date filters have many issues apart from this one and from my experience issues like this take years and years to progress, some look like they'll never be solved (check the entity reference filter issue for example where infra doesn't cope with the count of comments and d.o. results in a 404 every second request).
I thought it'll be best to start from contrib hoping it'll be a part of core one day.

It addresses the granularity issue by introducing "date" / "date and time" selector where date is converted to day range / ranges.
https://www.drupal.org/project/date_filter →

omarlopesino → closed merge request !3551

I had problems with #110 patch: the filter was not working correctly when filtering by month granularity at some specific months.
Patch #128 works for me and do not have that problem. But the tests do not pass. So I've created an MR applying patch from #128 fixing the issues that were producing the tests to fail; https://git.drupalcode.org/project/drupal/-/merge_requests/3552

I've also attached the patch + interdiff in case someone needs to check it.

I ran into issues saving the a view using a date filter with granularity when using the latest patch. I tracked the problem down to the views filter schema. The patch incorrectly sets the granularity property as integer in the schema, whereas it should be set to string. Changing the schema granularity property type to string fixes the issue. I'm uploading a new patch that fixes this. Other than that, this patch seems to be working great, thanks all!