[RomApp] Testing (with) RomManager

[Rbravo555]

📝 Description
So far we had been working in automating the construction of our ROMs using the RomManager, but were lacking a proper test for it. This PR is intended to provide it

Moreover, in this PR some of the tests have been convereted to be launched with the RomManager.

🆕 Changelog

• The RomManager was provided with some default values, so that one can instantiate it as

rom_mananger = RomManager()
rom_mananger.Fit()

This of course has some limitations, and sometimes the user should provide minimal inputs like the type of projection desired or the nodal unknown for the training which is by default [DISPLACEMENT_X, DISPLACEMENT_Y]

• refactored the test_structural_rom.py to use the RomManager

• refactored the test_thermal_lspg_rom.py to use the RomManager

• Added tests for the RomManager that check

  • that the defaults are being loaded
  • that the simulation is correctly orchestrated (structural)
  • that the files are created
  • the error raising