add open-usd exporter

[koubaa]

The API isn't so clean yet. An example script looks like this:

import ansys.mechanical.core as mech
project_file=r"D:\path\to\project.mechdat"

usda_file = r"D:\path\to\scene.usda"

app = mech.App(version=242, db_file=project_file)
app.open(project_file)

print(app)
from ansys.mechanical.core.embedding.viz.usd_converter import to_usd_file
print(f"converting {project_file} to usda at {usda_file}")
to_usd_file(app, usda_file)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.80%. Comparing base (6fb184a) to head (3edd5d7).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #701      +/-   ##
==========================================
- Coverage   77.56%   76.80%   -0.77%     
==========================================
  Files          31       31              
  Lines        1970     1970              
==========================================
- Hits         1528     1513      -15     
- Misses        442      457      +15