This patch also
- partially reverts commit f5c09ce0e6
that exposed a getTransports method on NetworkCapabilities.
- moves enumerateBits to BitUtils (as unpackBits), and adds the
reverse packBit method.
Bug: 34901696
Test: manually looked at $ adb shell dumpsys connmetrics list
Change-Id: Id04f9080e7f75608deeb49306aec34941e71794c