Add `prompt_file_save()` method

Add `prompt_file_save()` method to `MainFrame` class so that user can
rename output files after computation of various models.
Modify in order to prompt to rename output file

Modify in order to prompt to rename output file for all models in
`Dynamic` and `Identification` menus.
Update other functions accordingly to return the required parameters.
Modify in order to prompt rename of output file

Modify in order to prompt rename of output file for models in
`Geometric` and `Kinematic` menus.
Update other functions accordingly to return the required parameters.