[50 bounty] Move CAN ignition hooks and add test

[benksih-code]

Resolves #1834

Changes:

• Move ignition_can/ignition_can_cnt global variables from panda repo to opendbc safety layer
• Port full ignition_can_hook() implementation, 100% compatible with original panda code, no logic changes
• Automatically call ignition_can_hook() from safety_rx_hook() on all incoming CAN messages, same as panda behavior
• Add complete test coverage:
  • GM ignition signal (0x1F1) test
  • Rivian R1S/T GEN1 ignition signal (0x152 + counter validation) test
  • Tesla Model 3/Y ignition signal (0x221 + counter validation) test
  • Mazda ignition signal (0x9E) test
  • Negative test: ensure non-matching messages / non-bus 0 messages do not trigger false positives

All functionality matches existing panda implementation exactly, no breaking changes to any existing features or safety logic.

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