Move RingBuffer to SystemUICommon.

This change adds a new module SystemUICommon and moves RingBuffer to
it. This is to prepare introducing a new logging library which would
depend on it.

Bug: 276475093
Test: RingBuffer does not have existing tests, so just verified
LogBuffer works correctly on device

Change-Id: Ib71fcf8526021be1ac3fe279210c54cb7d4cd0e6
diff --git a/packages/SystemUI/common/OWNERS b/packages/SystemUI/common/OWNERS
new file mode 100644
index 0000000..9b8a79e
--- /dev/null
+++ b/packages/SystemUI/common/OWNERS
@@ -0,0 +1,2 @@
+darrellshi@google.com
+evanlaird@google.com