migrate to fastapi, improve HTML output

mc_openapi/assets/templates/base.html

mc_openapi/assets/templates/csp.html

mc_openapi/assets/templates/csp_content.html

mc_openapi/assets/templates/home.html

mc_openapi/assets/templates/mc.html

mc_openapi/doml_mc/exceptions.py

mc_openapi/doml_mc/imc.py

mc_openapi/doml_mc/intermediate_model/metamodel.py

mc_openapi/doml_mc/main.py

mc_openapi/doml_mc/mc_result.py

mc_openapi/doml_mc/xmi_parser/doml_model.py

mc_openapi/fastapi.py

mc_openapi/templates/csp.html.jinja

mc_openapi/templates/home.html

mc_openapi/templates/style.css

requirements.txt

tests/test_modelchecker.py