Implement BRD_PARAM_HIDE parameter

[tridge]

This implements two levels of parameter hiding, MAJOR and MINOR. There is a parameter BRD_PARAM_HIDE which controls what params are hidden, from 0 meaning none, to 2 meaning hide unset minor parameters. The default is to only hide major subsystems. This was to address a request from @DonLakeFlyer to make UIs easier. Note that the choice of which ones are major/minor are fairly arbitrary, and are currently chosen to suit places where param hiding is likely to cause UI issues for GCS implementations.

ping @lvale

UPDATE: this now implements _HASH_CHECK magic parameter as well. There may be some more parameters that should be marked as VOLATILE, plus we need a way to send the volatiles automatically

[WickedShell]

Default needs to be to unhide everything or it doesn't help a GCS on setup unless a GCS choose to just manipulate the parameter on the user (which it should never do)

[tridge]

@WickedShell Don was quite happy to have some things hidden, like Q_* I tried to pick the ones most likely to give UI issues btw, think your GCS changing the value is actually OK

[DonLakeFlyer]

Don was quite happy to have some things hidden, like Q_*

Yup. It's more of the vehicle setup oriented params which stabilize out after you set things from FRAME or turn on quad plane.

[WickedShell]

batt serial num is voltaile

[WickedShell]

Mission count and rally count are also volatile.

[tridge]

fixed serial num, rally and mission

[davidbuzz]

@tridge - is this still relevant?, rebase needed.

[peterbarker]

Pretty sure this is dead. Marking for DevCall anyway.

[peterbarker]

UTC2304 - https://github.com/ArduPilot/ardupilot/pull/8789
BRD_PARAM_HIDE option
For QGC
Make enable parameters / subtrees show up by default in QGC
Even with MP the reboot cycle is very painful
Rapid FTP download makes hidden parameters less useful
Rebooting to load driver is the really painful thing
Battery analogue pins is the poster-boy
Set to 4
Then reboot before battery pin and scale parameters turn up
Special case in battery monitor?
Monitor the parameter?
Best experience would subtree to instantly populate
First-time setup is cringe-worthy because of all the round-trips you have to do
And knowing the reboot-required / param fetfch stuff isn’t necessarily known