fix[cartesian]: Fix minimal k-range computation

[twicki]

Description

The computation of the minimal k-ranges that happen during the vaildate-args step is allowing for inconsistent computation to happen. This PR stiffens the requirements on fields:

• intervals [START+X ,END+y) are now also considered:
  • interval(3,-1) requires a minimal size of 5 for the interval to not be empty
  • interval(3,None) now requires a minimal size of 4
• intervals [START+X, START+Y) and [END+X,END+Y) are not affected.
• empty intervals are still allowed to have a 0-domain as to accomodate 2-dimensional fields
  • interval(...) still requires no k-size

Requirements

• All fixes and/or new features come with corresponding tests.

[romanc]

I am confused. In my mental model, min_k_size is the minimal height of the vertical column. Why do

def stencil_no_extent_1(field_a: gs.Field[float], field_b: gs.Field[float]):
    with computation(PARALLEL), interval(0, 2):
        field_a = field_b[0, 0, 0]

def stencil_no_extent_2(field_a: gs.Field[float], field_b: gs.Field[float]):
    with computation(PARALLEL), interval(1, 2):
        field_a = field_b[0, 0, 0]

both have a min_k_size of 2? Both have the same upper bound of 2, but the second one starts at the first level. I'd thus expect 2 for the first one and 1 for the second one. This was already before your changes, so maybe I don't understand correctly. What's wrong with my thinking?

[romanc]

Looks like include_center_interval is also never explicitly set in this function/visitor and its call tree. Remove it too for consistency?

Also, I can't mark the KBoundaryVisitor's doc string, but I think it should change too, no?

- """For every field compute the boundary in k, e.g. (2, -1) if [k_origin-2, k_origin+k_domain-1] is accessed."""
+ """For every field compute the boundary in k, e.g. (2, -1) if [k_origin+2, k_origin+k_domain-1] is accessed."""

[twicki]

done

[twicki]

re: docstring:

Nothing changes on this visitor, it still seems to hold up

[twicki]

I am confused. In my mental model, min_k_size is the minimal height of the vertical column. Why do

def stencil_no_extent_1(field_a: gs.Field[float], field_b: gs.Field[float]):
    with computation(PARALLEL), interval(0, 2):
        field_a = field_b[0, 0, 0]

def stencil_no_extent_2(field_a: gs.Field[float], field_b: gs.Field[float]):
    with computation(PARALLEL), interval(1, 2):
        field_a = field_b[0, 0, 0]

both have a min_k_size of 2? Both have the same upper bound of 2, but the second one starts at the first level. I'd thus expect 2 for the first one and 1 for the second one. This was already before your changes, so maybe I don't understand correctly. What's wrong with my thinking?

Sor for the second stencil to make sense, the domain in k need to have size 2. Otherwise the second interval would be empty.
Yes, the extent in which computation happens is only of size 1, but these checks are here to understand if the arguments to the call are compatible with the stencil definition, and this is why we need to check domain- and field-sizes