Move `buffered_scheduler` out of local (#157)

It's got nothing to do with "local", it is reusable just fine as-is in
distributed scenarios.
diff --git a/compiler_opt/distributed/local/buffered_scheduler.py b/compiler_opt/distributed/buffered_scheduler.py
similarity index 100%
rename from compiler_opt/distributed/local/buffered_scheduler.py
rename to compiler_opt/distributed/buffered_scheduler.py
diff --git a/compiler_opt/distributed/local/buffered_scheduler_test.py b/compiler_opt/distributed/buffered_scheduler_test.py
similarity index 97%
rename from compiler_opt/distributed/local/buffered_scheduler_test.py
rename to compiler_opt/distributed/buffered_scheduler_test.py
index 9c7be1a..0bd9b50 100644
--- a/compiler_opt/distributed/local/buffered_scheduler_test.py
+++ b/compiler_opt/distributed/buffered_scheduler_test.py
@@ -20,7 +20,7 @@
 
 from absl.testing import absltest
 from compiler_opt.distributed import worker
-from compiler_opt.distributed.local import buffered_scheduler
+from compiler_opt.distributed import buffered_scheduler
 
 
 class BufferedSchedulerTest(absltest.TestCase):
diff --git a/compiler_opt/rl/local_data_collector.py b/compiler_opt/rl/local_data_collector.py
index 20a72d2..eabdc72 100644
--- a/compiler_opt/rl/local_data_collector.py
+++ b/compiler_opt/rl/local_data_collector.py
@@ -23,7 +23,7 @@
 from tf_agents.trajectories import trajectory
 
 from compiler_opt.distributed import worker
-from compiler_opt.distributed.local import buffered_scheduler
+from compiler_opt.distributed import buffered_scheduler
 from compiler_opt.rl import compilation_runner
 from compiler_opt.rl import corpus
 from compiler_opt.rl import data_collector