double geofence vertices limit to 128

[ThomasRigi]

Follow-up of conversation on slack with @dagar on the maximum number of geofence vertices: https://px4.slack.com/archives/C0V533X4N/p1638198388018100

Describe problem solved by this pull request
We have found 64 vertices to be a too restrictive limit for some long-distance missions we fly.

Describe your solution
Increase the limit to 128.

Test data / coverage
On a Pixhawk 4 equipped with a Here2 GPS. I used perf counters to check the elapsed time when checking if inside the polygon. Tested with 8, 63 and 127 vertices.



The average time increases by about 20ms (+50%) for checking 127 vertices compared to 63. I think 60ms is still acceptable given that it's checked once every 200ms, but I'm not an expert on this.

Additional context
The open question is if the processor can handle to check up to 128 vertices. I only have Pixhawk 4 at my hand so I can't check for older processors.