EAMxx: upgrades to DataInterpolation

[Copilot]

Add two features to DataInterpolation:

• Ability to inteprolate non-time-dependent data
• Ability to pick a start timestamp for YearlyPeridic when the database spans 2+ years.

[BFB]

---

Fixes #7619

Luca: While copilot took the first stab, I did most of the cleanup and polishing, so I'm removing myself as a reviewer. Here's a summary of what this PR does:

1. allow to read in non-time-dependent data
2. for YearlyPeriodic timeline, allow to specify a start date for the 12 months to use.
3. Split setup_time_database into two methods: the periodic one can take the extra "start_ts" arg, which makes no sense for linear history.
4. The time interpolation type (Linear vs Nearest) concerns the time interpolation interval, not the time database, so now it's passed to init_time_interpolation, which is the new name of init_time_interval.

[Copilot]

Pull request overview

This PR upgrades EAMxx’s DataInterpolation utility to support both (1) true
time-independent (“static”) inputs and (2) improved YearlyPeriodic handling when
input datasets span multiple years (via a start_ts selection mechanism). It
also refactors and expands the unit tests to cover these new modes and to
increase parallel test throughput.

Changes:

• Introduces a clearer DataInterpolation setup API by splitting time-dependent
  setup into setup_linear_time_database / setup_periodic_time_database and
  adding setup_static_database, plus new init/run entry points for static vs.
  time-dependent usage.
• Implements a static-data execution path that reads once and then remaps
  without requiring a timeline/interval.
• Refactors/splits the former monolithic data interpolation test into multiple
  focused test executables and expands coverage (static data, start_ts
  selection/rotation behavior, etc.).

Reviewed changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
components/eamxx/src/share/algorithm/eamxx_data_interpolation.hpp	New public API for linear/periodic/static databases; new init/run entry points.
components/eamxx/src/share/algorithm/eamxx_data_interpolation.cpp	Implements static path, periodic pruning logic, refactors reader setup, and updates interpolation runtime.
components/eamxx/src/share/algorithm/tests/data_interpolation_tests.hpp	Shared test helpers updated for multi-file/multi-year and static testing.
components/eamxx/src/share/algorithm/tests/data_interpolation_tests.cpp	Removes the old monolithic test file (tests are split into multiple new files).
components/eamxx/src/share/algorithm/tests/data_interpolation_setup.cpp	Generates additional time slices/files and new static (no-time-dim) test inputs.
components/eamxx/src/share/algorithm/tests/data_interpolation_exceptions_tests.cpp	Split-out exception coverage updated to new API.
components/eamxx/src/share/algorithm/tests/data_interpolation_periodic_linear_tests.cpp	Split-out YearlyPeriodic+Linear test coverage.
components/eamxx/src/share/algorithm/tests/data_interpolation_periodic_nearest_tests.cpp	Split-out YearlyPeriodic+Nearest test coverage.
components/eamxx/src/share/algorithm/tests/data_interpolation_linear_hist_linear_tests.cpp	Split-out Linear timeline + Linear interpolation test coverage.
components/eamxx/src/share/algorithm/tests/data_interpolation_linear_hist_nearest_tests.cpp	Split-out Linear timeline + Nearest interpolation test coverage.
components/eamxx/src/share/algorithm/tests/data_interpolation_static_tests.cpp	New tests for static (time-independent) interpolation and snapshot selection.
components/eamxx/src/share/algorithm/tests/data_interpolation_start_ts_tests.cpp	New tests for start_ts behavior in YearlyPeriodic databases.
components/eamxx/src/share/algorithm/tests/CMakeLists.txt	Splits the test target into multiple executables for parallelism and adds new tests.
components/eamxx/src/physics/spc/eamxx_spc_process_interface.cpp	Updates SPC to the new DataInterpolation setup/init API.
components/eamxx/src/physics/spa/eamxx_spa_process_interface.cpp	Updates SPA to the new DataInterpolation setup/init API.
components/eamxx/src/physics/mam/eamxx_mam_microphysics_process_interface.cpp	Updates MAM readers to the new DataInterpolation setup/init API.