systemui: separate proguard files into multiple ones

- Keep proguard_common still containing all of them.
- To allow customization per form factor with only inclusion of
  proguard_common_core.flags.
- Minor bp lint fix using bpfmt for SystemUIPluginLib

Flag: NONE
Test: build
Bug: 301283783
Change-Id: Idf352e7bfe542d263ad2ef4c1cda80d818ed54e6
diff --git a/packages/SystemUI/plugin/proguard_plugins.flags b/packages/SystemUI/plugin/proguard_plugins.flags
new file mode 100644
index 0000000..abac27f
--- /dev/null
+++ b/packages/SystemUI/plugin/proguard_plugins.flags
@@ -0,0 +1,9 @@
+# The plugins and core log subpackages act as shared libraries that might be referenced in
+# dynamically-loaded plugin APKs.
+-keep class com.android.systemui.plugins.** {
+    *;
+}
+
+-keep class com.android.systemui.log.core.** {
+    *;
+}