Create directory for /data/misc/connectivityblobdb

Create a new folder for connectivity blobs, to be used by
ConnectivityBlobStore for VPN and WIFI to replace legacy
keystore. System server and Settings app will need permissions
to manage databases in the folder.

Bug: 307903113
Test: build and manual test to confirm folder is created.
Change-Id: I3b558d8d5913e0d3d1efe5cb56d5f7f2e84fd22a