Fix/enhance NMEA & Ublox message polling for GPS

[KarateBrot]

This PR fixes some bugs/problems on both NMEA and U-blox protocols to make DOP values work properly. In addition I refactored the code to save some flash and added the U-blox accuracy estimate for position to the GPS solution for use in BF.

The commit names describe in detail what I changed.

Thanks a lot to @ctzsnooze for laying the groundwork for this PR and identifying the problems.

Also thanks a lot to the testers: @benjamind2 and Sek101

[benjamind2]

Tested, works, provided Debug=GPS_DOP log on discord, from commit e521d748b2060b7fd0db9ee204a4fb69fb990d2c.

Used "Flywoo GM8 Mini V2.0 GPS Module" at 115200 baud on a F7X2 SkyStars FC.

Observed very fast lock, but that could be coincidental. Coordinate map, speed, satellites, altitude, distance from home all look good, meet or exceed previous behavior.

[KarateBrot]

@benjamind2 Thanks for testing! You tested this with the UBlox protocol, so now we need to make sure this also works on the NMEA protocol 👍

Edit:
Benjamin tested this on NMEA as well and we are getting valid DOP values (Discord conversation). DOP values are now confirmed to work on UBlox and NMEA.

But there is a bug where velocity for GPS Rescue gets now updated by several GPS messages with different values. There is a fix ready for testing. Tomorrow we will know more.

[github-actions]

Do you want to test this code? Here you have an automated build:
Assets
WARNING: It may be unstable. Use only for testing! See: https://www.youtube.com/watch?v=I1uN9CN30gw for instructions for unified targets!

[blckmn]

AUTOMERGE: (FAIL)

• github identifies PR as mergeable -> PASS
• assigned to a milestone -> PASS
• cooling off period lapsed -> PASS
• commit count less or equal to three -> FAIL
• Don't merge label NOT found -> PASS
• at least one RN: label found -> PASS
• Tested label found -> PASS
• assigned to an approver -> PASS
• approver count at least three -> PASS

[KarateBrot]

But there is a bug where velocity for GPS Rescue gets now updated by several GPS messages with different values. There is a fix ready for testing. Tomorrow we will know more.

Sek101 confirmed with logs that it is now fixed