Add support for the u-Blox ZED-X20P GNSS module

[adpjhu]

Feature request

Is your feature request related to a problem? Please describe.
No

Describe the solution you'd like
Add support for the u-Blox ZED-X20P GNSS module in AP_GPS / UBLOX .

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Platform
[ X ] All
[ ] AntennaTracker
[ ] Copter
[ ] Plane
[ ] Rover
[ ] Submarine

Additional context
This module is the latest version from u-Blox and it supports L1/L2/L5/L6 with RTK. It has current support for u-Blox Point Perfect corrections service (IP and L-band) and future support for in Q1 26 for centimeter positioning with Galileo High Accuracy services delivered via E6b.

[adpjhu]

Looks like this is in progress here: Existing PR #31217
Discord Channel https://discord.com/channels/674039678562861068/1412219935890866256