Accept test targets when working with the simulators command

[premun]

XHarness simulators command now also accepts target runtimes in the same format as test targets. These formats are now equivalent:

• com.apple.pkg.iPhoneSimulatorSDK14_3
• ios-simulator_14.3

There is also a breaking change for the install and find commands - we now accept the list of simulators as positional arguments instead of --simulator arguments. The new usage is this:

xharness apple simulators install ios-simulator_14.3 tvos-simulator_11.6

Resolves #478

[premun]

/cc @mattleibow

[mattleibow]

The other commands also allowed for the bit size, so not sure if that is relevant or needs consistency :

ios-simulator-64_14.3

This might be relevant for watch things since I am not sure if any other architectures exist other than 64

[premun]

@mattleibow it doesn't matter for the package names, I think you just need to install old enough version that are 32-bit if I am not mistaken.

However, I also allowed to enter ios-simulator-64 and -32 so that you can have it easy in the build and call both commands with the same target:

xharness apple simulators install ios-simulator-64_14.2
xharness apple test --target=ios-simulator-64_14.2 ...