[runtime] Initialize thread suspend policy at startup, inline getter (#16149)
* [runtime] Initialize thread suspend policy at startup, inline getter
On some benchmarks we saw mono_threads_suspend_policy() using a lot of CPU
time.
Rather than doing an init-on-first-use, initialize the policy once upfront when
the JIT it starting up and make the getter method static inline.
* move mono_threads_suspend_policy_init into mono_thread_info_init
* [mini] Initialize suspend policy for `mono --version`
Need to initialize the suspend policy before printing its name. Otherwise the
suspend policy is unset since no other runtime initialization is done for `--version`.