Implement a columnwise shmem operator

[charleskawczynski]

This PR abstracts all but the physics from CliMA/ClimaAtmos.jl#3655, and implements columnwise!.

This operator can be used to assign a large number of broadcast operations, all within the same kernel.

The idea is that we can use this function

• once in implicit_tendency! (which will set all of the tendencies in a single kernel)
• 2 or 3 times in remaining_tendency! (before / after dss, before / after horizontal terms)

Some preliminary results from the dry baro wave:

unfused & multiple broadcasts (set-precomputed + implicit): 4.31997 ms
single fused broadcast without shmem: 7.18 ms
single fused broadcast with shmem for state: 3.47 ms
single fused broadcast with shmem for state + LG: 4.73 ms
single fused broadcast with shmem for state + needed parts of LG: 3.93 ms

For ldiv! and wfact!, I think we may need to rethink their implementations.

The only optimizations I've done in this operator is shared memory. There is probably a lot of room in tuning and improving memory access. A big benefit of this approach is that this will drastically reduce the number of kernel launches, and sequential memory reads.

This approach also helps push us towards CliMA/ClimaAtmos.jl#3594.