Add BSM support for Hyundai Ioniq 6

[whoisdomi]

Problem
Blind Spot Monitoring was not working on 2023-24 Hyundai Ioniq 6 despite the car having BSM hardware and comma detecting "Blind Spot Support: Yes" in Vehicle Info.

Root Cause
Wrong fingerprint message - BSM detection checked for message 0x1e5 (BLINDSPOTS_FRONT_CORNER_1) which doesn't contain the blind spot indicator signals

The original code had a logic mismatch:

Fingerprinting checked for 0x1e5:

ret.enableBsm = 0x1e5 in fingerprint[CAN.ECAN]
#But reading tried to get signals from 0x1ba:
ret.leftBlindspot = cp.vl["BLINDSPOTS_REAR_CORNERS"]["FL_INDICATOR"] != 0 # 0x1ba!

Wrong signal names - Ioniq 6 uses different signals (LEFT_MB/MORE_LEFT_PROB) than other CAN FD cars (FL_INDICATOR/FR_INDICATOR) for blind spot detection

Fix
interface.py: Changed BSM fingerprinting from 0x1e5 to 0x1ba (BLINDSPOTS_REAR_CORNERS)
carstate.py: Added car-specific signal handling for Ioniq 6

Changes

interface.py - Use correct BSM message for fingerprinting

ret.enableBsm = 0x1ba in fingerprint[CAN.ECAN]

carstate.py - Ioniq 6 uses different BSM signals

if self.CP.carFingerprint in (CAR.HYUNDAI_IONIQ_6,):
ret.leftBlindspot = cp.vl["BLINDSPOTS_REAR_CORNERS"]["LEFT_MB"] != 0
ret.rightBlindspot = cp.vl["BLINDSPOTS_REAR_CORNERS"]["MORE_LEFT_PROB"] != 0
else:
ret.leftBlindspot = cp.vl["BLINDSPOTS_REAR_CORNERS"]["FL_INDICATOR"] != 0
ret.rightBlindspot = cp.vl["BLINDSPOTS_REAR_CORNERS"]["FR_INDICATOR"] != 0

Tested
Verified on 2023 Hyundai Ioniq 6 with HDA II
BSM border metrics display correctly
Blind spot path overlay works
No CAN errors

[github-actions]

Thanks for contributing to opendbc! In order for us to review your PR as quickly as possible, check the following:

• Convert your PR to a draft unless it's ready to review
• Read the contributing docs
• Before marking as "ready for review", ensure:
  • the goal is clearly stated in the description
  • all the tests are passing
  • include a route or your device' dongle ID if relevant

[sunnyhaibin]

Generally, you'd want to match the CAN ID that carstate is using for BSM, in case certain platforms don't have anything going on with the BSM signals defined in carstate.