DNM: Yet another simulator pool implementation

[maxwellE]

This works as follows

add a rule like follows

load(
    "@build_bazel_rules_apple//apple/testing/simulator_pool:create_simulator_pool.bzl",
    "create_simulator_pool"
)
load(
    "@build_bazel_rules_apple//apple/testing/default_runner:ios_xctestrun_runner.bzl",
    "ios_xctestrun_runner"
)

ios_xctestrun_runner(
    name = "ios_x86_64_sim_runner",
    device_type = "iPhone Xs",
)

create_simulator_pool(
    name = "create_simulator_pool",
    device_type = "iPhone Xs",
    pool_size = 3,
    os_version = "18.3",
    server_port = 50051,
)

ios_xctestrun_runner(
    name = "simulator_pool_test_runner",
    device_type = "iPhone Xs",
    simulator_pool_server_port = 50051,
)

You will need to make sure you consume :simulator_pool_test_runner in your ios_unit_test rule

You also need to create the pool and its server by running the following before you run any tests

bazel run //:create_simulator_pool

This will automatically daemonize the server. Once you are done with the pool you need to run

curl -X GET http://localhost:50051/shutdown to shut the server down.

The server shutdown does not delete any simulators. On startup the server automatically deletes old cloned simulators and makes new clones off of the originally booted golden simulator. A golden simulator is one which is never deleted, it is only booted and shutdown to be used for testing or cloning to other simulators.