allow lua apps to keep key/value data in model yaml

[offer-shmuely]

Is there an existing issue for this feature request?

• I have searched the existing issues

The problem

apps like "Flight count" elrs-setup, flight-history need to keep data for their operation
the data is related to specific model, but currently cannot be kept there
over the year workaround where developed:

• keep flight number on GV9
• keep history data on csv file
• keep flight-controller name on csv file

Describe the solution you'd like

Implement key/value, that will be save and retrieve on the yaml file (they do NOT need to be kept on the memory)

write apps properties.

model.appPropertySet(appName, key, value)
Parameters

• appName (string) - the name of the app
• key (string) – name of the property.
• value – value to be set

retrieve app property by name.

app.appPropertyGet(appName, key)
Parameters

• appName (string) - the name of the app
• key (string) – name of the property
  Return: the value

remove all app properties .

app.appPropertyDelete(appName)
Parameters

• appName (string) - the name of the app
  Return: the value

Samples:

model.appPropertySet("FlightApp", "flight_count", 25)
local v = model.appPropertyGet("FlightApp", "flight_count")

model.appPropertySet("RF2_Info", "flight_controller_name", "Sab Goblin 700")
local v = model.appPropertyGet("RF2_Info", "flight_controller_name")

model.appPropertySet("RF2_Info", "last_know_image_name", "heli700")
local v = model.appPropertyGet("RF2_Info", "last_know_image_name")

model.appPropertyDelete("RF2_Info")