Add arm64 to list of compatible watchOS architectures since Apple Silicon machines will create arm64 watch simulators. This change also dynamically determines the target architecture when building for watch simulators because Xcode sets both x86_64 and arm64 when building for watch simulator so we need to dynamically determine the architecture we need based on the architecture of the host machine. #381
PiperOrigin-RevId: 468340824 (cherry picked from commit 6e039178388e436f8d61e0bcff7adc750d41db4e)
Conflicts: src/TulsiGenerator/DeploymentTarget.swift src/TulsiGenerator/Scripts/bazel_build.py