Fix memory issues

[dennisYatunin]

This PR reduces ClimaCore memory usage due to excessive code inlining, and it closes #1064.

Specifically, it

• Removes the @inline annotations to Base.copyto! that were added in Inline copyto! to fix Ref allocations #945 and Extend and fix Ref broadcasting with StencilCoefs #978.
• Removes all slurm_mem increases from the CI pipeline, so that the default value of 8GB applies to every task.
• Extends broadcasting over Fields and DataLayouts so that it can handle single-element Tuples. In theory, broadcasting with a single-element Tuple should be equivalent to broadcasting with a Ref. However, since a Ref is mutable, it looks like the compiler needs to perform runtime allocations when using a Ref, unless we force it to inline the majority of the broadcasting machinery.
• Replaces every Ref in test/Fields/field_opt.jl with a single-element Tuple, so that the runtime allocation unit tests can pass.
• Replaces two of the @test_brokens in test/Operators/finitedifference/opt_examples.jl with @tests, since those tests are now passing, even though they don't appear to have anything to do with Refs.

Note: It is still necessary to go through the rest of our code (both in ClimaCore and elsewhere) and replace every Ref in a Field/DataLayout broadcast with a single-element Tuple. Now that the @inline annotations have been removed, broadcasting with a Ref will trigger runtime allocations, which will pose a problem for our long runs.

• Code follows the style guidelines OR N/A.
• Unit tests are included OR N/A.
• Code is exercised in an integration test OR N/A.
• Documentation has been added/updated OR N/A.

[simonbyrne]

bors try

[bors]

try

Build succeeded:

• lib-climacore-makie
• lib-climacore-plots
• buildkite/climacore-ci
• test-os (macos-latest)
• lib-climacore-vtk
• format
• test-os (ubuntu-20.04)
• test-os (windows-latest)
• lib-climacore-tempestremap
• docbuild

[dennisYatunin]

bors try

[bors]

try

Build failed:

• test-os (macos-latest)

[dennisYatunin]

bors r+

[bors]

Build succeeded:

• buildkite/climacore-ci
• docbuild
• format
• lib-climacore-makie
• lib-climacore-plots
• lib-climacore-tempestremap
• lib-climacore-vtk
• test-os (macos-latest)
• test-os (ubuntu-20.04)
• test-os (windows-latest)

[charleskawczynski]

I think it would have been better if we had added new tests in this PR, and converted any passing tests to failing tests, rather than change existing tests, which makes understanding the changes more complicated.