EAMxx: add support for rank-0 fields in compute_mask

[bartgol]

It is needed in IO when outputing 0d fields.

[BFB]

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Fixes #7912

[Copilot]

Pull request overview

This PR adds support for rank-0 (scalar) fields in the compute_mask function, which is needed for IO operations when outputting 0-dimensional fields. The implementation is marked as bit-for-bit (BFB) and addresses issue #7912.

• Added rank-0 field handling in the contiguous case with appropriate Kokkos parallel_for implementation
• Updated error message checks to allow rank-0 fields (changed f.rank()>0 and f.rank()<=6 to f.rank()<=6)
• Enhanced error messages with field names and rank information for better debugging
• Added comprehensive test coverage for rank-0 fields testing all comparison operations

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
components/eamxx/src/share/field/utils/compute_mask.cpp	Implements rank-0 field support in the compute_mask template function, relaxes rank validation to allow rank 0, improves error messages with field metadata, and adds case 0 handlers for all data types
components/eamxx/src/share/field/tests/compute_mask.cpp	Adds comprehensive test coverage for rank-0 fields, including field identifiers for 0d cases and a new test section that validates all comparison operations (EQ, NE, GT, GE, LT, LE)

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