Improve device selection when using 'dotnet run'

[rolfbjarne]

Currently selecting which device or simulator to run on when launching from the command line is not ideal:

• Pass -p:_DeviceName=<udid> when targeting a device
• Pass -p:_DeviceName=:v2:udid=<udid> when targeting a simulator

This should be unified to have the same format, and also use a non-underscored property name. Maybe also share the property name with Android.

Ideas for the property name:

• Device: is the simulator a device? Would this be confusing?
• Target: closer to Android, but seems maybe a bit unspecific?
• TargetDevice: same as Device, but it's also longer and sounds a bit worse I think
• other ideas?

Ideas for the format:

Just pass the udid as-is and figure out what to do, so this works on both simulator and device:

$ dotnet run -p:Device=<udid> ...

And "udid" can be the name of the device too, if it's unique.

For reference, I think Android currently does this:

• -p:AdbTarget=...

References:

• Figure out 'dotnet run' CLI experience for iOS and Android xamarin#26

CC @jonathanpeppers

[jonathanpeppers]

Android is bad, too, as it is -p:_AdbTarget and then you have to escape a space inside the value.