[pt2] Add meta for poisson (pytorch#134103)

Because aten.poisson doesn't have meta function registered, there is one additional eager execution of this op during compilation phase of torch.compile.

There are more ops without meta registration. Is there any reason for it?
Pull Request resolved: pytorch#134103
Approved by: https://github.com/ezyang

torch/_meta_registrations.py

@@ -2060,6 +2060,12 @@ def meta_bernoulli_p(self, p=0.5, generator=None):
     return torch.empty_like(self).contiguous()
 
 
+@register_meta([aten.poisson.default, aten.poisson.out])
+@out_wrapper()
+def meta_poisson(self, generator=None):
+    return torch.empty_like(self)
+
+
 @register_meta(aten._fused_moving_avg_obs_fq_helper.default)
 def meta__fused_moving_avg_obs_fq_helper(
     self,