FEATURE: add templates for examples

[SMoraisAnsys]

While working on making examples working with the new documentation workflow, I noticed that our examples do not follow the same template at all. I think it could be great to have an example template from which every example should "inherit".

Here is a list of stuff/sections that should be contained:

• imports
• define extra class / function used in the example
• setup environment : tempfile + download (if needed)
• setup the app
• make all the processing
• cleanup : save project and remove tempfile

Since we will have multiple type of examples it would be nice to start with:

• pyaedt examples related to EDB (see FEAT: add example template and writer #5)
• general pyaedt examples (might lead to HFSS ones, Q3D ondes, ...)

Note: this templates could also be used in the CI to roughly check that a provided new example matches some expected template !

[Samuelopez-ansys]

#154