Add support of PicoScope 3000 series + MSO (16chan option)

[bvernoux]

No description provided.

[azonenberg]

SERIES_UNKNOWN is no go. You need to define a series for the scope so we know what it is and can figure out what features are available.

Also, corresponding work is probably needed in the bridge. Someone tried to use the bridge not long ago with a 3000 series and had a bunch of trouble. Among other things, the function generator code was giving errors because there's no 3000 series backend for it. So that needs to be either disabled or implemented for 3000 series depending on whether 3000 has a func gen.

[bvernoux]

I have pushed for test:

• Add support of Picoscope 3000 series (including MSO option)
• See also https://github.com/bvernoux/scopehal-pico-bridge
  • Add support of Picoscope 3000 series (including MSO option) (missing AWG)
  • See Support Picoscope3000 series+MSO (missing AWG) scopehal-pico-bridge#19

[bvernoux]

I confirm all work fine on my PC tested with Windows10 and Picoscope 3406DMSO (I still need to test the 16x MSO channels, I have checked 4 Analog channels works fine)

[bvernoux]

@azonenberg this PR is ready for merge