chore: refactorings for Python 3.10 as minimum version

[phanak-sap]

• [PEP 604] Replace isinstance(x, (A, B)) with isinstance(x, A | B) — service.py lines ~1306 and ~1711
• [PEP 634 / HIGH] Refactor _build_expression operator dispatch to match/case — service.py (removes
  too-many-return-statements, too-many-branches pylint suppression)
• [PEP 634 / HIGH] Refactor MetadataBuilder.build() XML type dispatch to match/case — model.py ~line
  2737
• [PEP 634 / MEDIUM] Refactor function_import_handler return-type dispatch to match/case — service.py
  ~line 1711
• [PEP 634 / MEDIUM] Refactor navigation property multiplicity dispatch to match/case — service.py ~line
  859
• [PEP 634 / LOW] Refactor ValueHelper.from_etree annotation property dispatch to match/case —
  model.py ~line 2473
• [CLEANUP] Replace all super(ClassName, self) with super() — 46 locations across exceptions.py,
  model.py, service.py, vendor/SAP.py