[Web] Tutorial for mimicking a moving boundary condition

This MR adds a tutorial, which describes an example workflow for mimicking a moving boundary condition

This tutorial describes the implementation in OGS of a method for mimicking the behavior of a moving Dirichlet boundary condition, applicable to HeatConduction processes. Moving Dirichlet boundary conditions are useful, for example, to emulate the rise during construction of a thermally-active structure, e.g., a landfill embankment or a sulfide tailings dam.

Testing:

• via vtkdiff in the prj-file at the last timestep
• Assertion for the results from the source_term.py to check the correct data for the last figure

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