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Refactor and relax filtering of known undialable addresses

This commit moves filtering of dial candidates into its own little function.
Things that are being filtered: addresses configured to be blocked,
IPv6 link-local addresses, addresses without a dial-capable transport,
and addresses that we know to be our own. It's is an optimization to
avoid wasting time on dials that we know are going to fail.

This also relaxes the filtering of addresses that we consider our own.
Previously, any address would get filtered that's registered in peerstore
for or own PeerID. For e.g. /ip4/1.2.3.4/tcp/4001 that's fine, but for
ephemeral ports it can already cause problems.

In addition, now that go-libp2p-circuit is being fixed to handle its
multiaddrs slightly differently, /p2p-circuit addresses won't contain
the PeerID anymore. That means they stand for themselves, and would get
filtered too. (/p2p-circuit is the address we want to dial, but it's
also on of "our own addresses").

In the future we'd want to use the mafmt package here, and also consider
/quic, /ws, etc. addresses as our own.

log an error when we have no transports configured

Modify our two transport lookup functions to log loudly when there are no
transports registered.

Issue #370 Check if empty peer ID

On trying to open a new stream against an empty peer ID, we get an
error saying that failed to dial a peer.

This commit changes that to a more informative error message:
`empty peer ID`

remove redundant dial timeout

This timeout is already set by the dial limiter.

improve timeouts

The global per-peer dial timeout had a significant drawback: When dialing many
peers, this timeout could cause libp2p to cancel dials while they were still
stuck in the limiter.

A better but more complicated approach is a time budget system but we can
implement that later.

This change simply applies the limit to each `DialPeer`/`NewStream` call
independently and makes it easy to override. While old timeout tried to
account for how much we're willing to spend dialing a single peer, this new
timeout tries to account for the amount of time a single "client" is willing to
wait for a dial to complete before they no longer care.