Move SdkExtensions/proto to packages/modules/common.

The proto definitions may be needed at build time to generate appropriate
configs for the modules. Unbundled ART branches do not include
packages/modules/SdkExtenstion in their manifest; so put the proto in a
project that should be visible to all unbundled modules.

Move any relevant tools to packages/modules/common/tools as well.

Bug: 180105615
Test: m nothing
Change-Id: I4efa4300553af6b321f46adb29b8cc90e4556955

tools/gen_sdkinfo.py

@@ -0,0 +1,19 @@
+import sdk_pb2
+import sys
+
+if __name__ == '__main__':
+  argv = sys.argv[1:]
+  if not len(argv) == 4 or sorted([argv[0], argv[2]]) != ['-o', '-v']:
+    print('usage: gen_sdkinfo -v <version> -o <output-file>')
+    sys.exit(1)
+
+  for i in range(len(argv)):
+    if sys.argv[i] == '-o':
+      filename = sys.argv[i+1]
+    if sys.argv[i] == '-v':
+      version = int(sys.argv[i+1])
+
+  proto = sdk_pb2.SdkVersion()
+  proto.version = version
+  with open(filename, 'wb') as f:
+    f.write(proto.SerializeToString())