Update the Getting Started section for the svMultiPhysics updates

[ktbolt]

Problem

The Getting Started section of the documentation needs to be updated to use the svMultiPhysics solver and remove references to svSolver and svFSI.

Solution

Update the Getting Started documentation.

Additional context

No response

Code of Conduct

• I agree to follow this project's Code of Conduct and Contributing Guidelines

[ktbolt]

I've renamed the quickguide doc directory to getting_started and updated the docs to use MultiPhysics.

I've replaced just a few of the SV GUI images with the latest SV version, will replace the others later.

[ktbolt]

I've removed the Getting Started CFD Simulation sub-section, will later add that to the CFD Simulation guide.