Support iOS Simulator Arm64 Target

Hello! I tried using the runtime artifact in a project that I recently started working on. Since I'm using a simulator on an M1 MacBook, I'll need to be able to build against the iosSimulatorArm64 target (at least, to be able to run the project in the simulator).

I'm thinking the target can simply be added to the build.gradle file:

def iosTargets = [
    iosArm64(),
    iosSimulatorArm64(),
    iosX64(),
]
iosTargets.each { target ->
    target.binaries {
        framework {
            baseName = "Thrifty"
        }
    }
    target.compilations.main.cinterops {
        KT62102Workaround {}
    }
}

Edit: realizing that the style change above is against the contributions guidelines but I think it still gets the point across. :) Otherwise:

iosSimulatorArm64 {
    binaries {
        framework {
            baseName = "Thrifty"
        }
    }
    compilations.main.cinterops {
        KT62102Workaround {}
    }
}

Start in build.gradle and inspect the existing iOS targets and their framework and cinterop configuration. Add the iosSimulatorArm64 target consistently with the current setup, then verify that the runtime artifact can be built for an M1 simulator.