[RomApp] coupled fluid-thermal & thermo-mechanical complete rom hrom workflow with rom manager

[Rbravo555]

📝 Description

Support for coupled fluid-thermal ROMs was added in PR #14573. This PR adds the full construction workflow for coupled simulations to RomManager, and extends coupled support to thermo-mechanical problems.

Coupled problems are declared through a top-level coupled_solvers list, with one entry per sub-solver. Each entry can override some of the general ROM/HROM settings:

"coupled_solvers": [
    {"sub_solver_name": "fluid_solver"},
    {"sub_solver_name": "thermal_solver",
     "ROM":  {"model_part_name": "ThermalModelPart", "nodal_unknowns": ["TEMPERATURE"]},
     "HROM": {"element_selection_svd_truncation_tolerance": 1e-5}}
]

If the list is omitted, the solvers are detected from the ProjectParameters.json. A single (monolithic) basis is built from the union of the solvers' nodal_unknowns. For the HROM, one set of elements and conditions is selected, with one set of weights per physics.

Coupled ROMs currently support linear decoders only.

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🆕 Changelog

• Feature: coupled_solvers list in the RomManager parameters, with validated per-solver ROM/HROM overrides.
• Feature: One ECM per solver in RomManager, giving a single element set with one set of weights per physics (builds on PR [RomApp] Change HROM_WEIGHT variable to Vector type #14756).
• Feature: ROM and HROM support for thermo-mechanical coupled problems.
• Fix: rom_analysis injects the ROM settings into each sub-solve
• Tests: Coupled RomManager training test, coupled_solvers validation tests, and thermo-mechanical ROM/HROM tests.

[Marco1410]

LGTM.
Approved, so we can move forward.
Thanks Raul.