[GeoMechanicsApplication] Generalize the C++ workflow

[deltaresmf]

At present, we have two C++ workflows: one for flow analyses and one for settlement analyses. The former is less general, since it contains some hard-coded values as well as a process that is not accessible from Python. The latter contains processes that are needed for settlement analyses, but nothing stops us from adding more processes in order to make the workflow more general (as was also demonstrated by Carlos's prototype branch).

As a developer, I'd like to have a single C++ workflow for geotechnical analyses, where all the relevant analysis data is taken from the input files rather than being hard-coded. This generalized workflow should accept a list of processes that are relevant to any specific analysis type (flow analysis, settlement analysis, stability analysis, etc.). Such specific analysis types (like the current flow and settlement analysis types) should sit on top of the generic C++ workflow. Our users can continue to use the existing C++ workflows, which under the covers delegate the work to the extracted generic C++ workflow.

[indigocoral]

@avdg81 will fill this with more details.

Comment by @avdg81 on February 11, 2026: I've updated the title of this issue, and I've briefly explained the idea in the description. This issue should be understood to be a user story. Sub-issues will need to be added to break down the actual work.