VW MLB: Porsche Macan

[jyoung8607]

Goals for dashcam-only merge

• [ ] Cleanup and optimize factoring together with MQB and upcoming MQBevo/MEB
• [ ] Checksum validation, split CRC functions because older messages use XOR and overlap with MQB
• [ ] Replace ACC message with TSK message for engagement state
• [x] Gearshift position from Getriebe_03.GE_Waehlhebel
• [x] Door-open states (bus position may force a compromise here)

Future goals (may not happen in this PR)

• [ ] Handle camera harness integration (currently only gateway)
• [ ] HCA timeout mitigation (same basic issue as VW PQ, same mitigation works)
• [ ] Fuzzy fingerprinting based on Porsche VIN format
• [x] Research and handle apparent minor variances between Macan model-years
• [ ] Longitudinal control (long-term, might de-scope from this PR)