Teach clang-format the right import statement order.

Taken from
https://source.android.com/docs/setup/contribute/code-style#order-import-statements.

#codehealth

Test: clang-format on http://ag/20333208
Change-Id: I1378293bbc0a6b7a3482f9bd0beb71f95e11809d
diff --git a/.clang-format b/.clang-format
index 03af56d..d60d33c 100644
--- a/.clang-format
+++ b/.clang-format
@@ -9,5 +9,17 @@
 ConstructorInitializerIndentWidth: 6
 ContinuationIndentWidth: 8
 IndentWidth: 4
+JavaImportGroups:
+- android
+- androidx
+- com.android
+- dalvik
+- libcore
+- com
+- junit
+- net
+- org
+- java
+- javax
 PenaltyBreakBeforeFirstCallParameter: 100000
 SpacesBeforeTrailingComments: 1