getIPOnly() is more efficient for pure IP addresses (no hostnames)

similar to previous checkin for relay intro

- Return OK as Alice when only receiving msg 5, unless snatted (SSU 1 also)
- Allow and handle firewalled Charlie as Alice
- Only create peer test data once as Alice
- Store test status and send-to-Alice time in test state to support retransmission
- Don't delete state after sending msg 4 as Bob, for possible retransmission
- Check for IP mismatch from Charlie as Alice, abort test and assume good
- Check for port mismatch from Charlie as Alice and validate
- Skip unroutable addresses when searching through RI for the right one
- Respond to retransmitted msg 1 as Bob
- Respond to retransmitted msg 2 as Charlie
- Update Charlie timer to retransmit msg 5
- Only send Charlie RI to Alice (as Bob) if test was accepted
- Convert timers to SimpleTimer2 (SSU 1 also)
- Log tweaks

Most changes are relevant only if NTP is disabled or failed at startup.

- Require two peers that agree for transports to initialize time
- Briefly ban skewed peer when not initialized, so another peer will be the second sample
- Allow SSU2 to initialize time even for large skews
- Do not allow NTCP2 inbound to initialize time for large skews
- Disable SSU1 time initialization when SSU2 is enabled
- When SSU2 is disabled, allow SSU1 time initialization even for large skews
- Don't adjust to large inbound NTCP2 skews when not initialized
- Round time sent in NTCP2 DateTime block
- Adjust SSU2 skew for RTT
- Don't sort by absolute skew on SSU /peers tab so we can find median
- Only call System.currentTimeMillis() once in RouterClock.setOffset()
- Log tweaks

as Bob, to send to Charlie, if it fits.
Otherwise, delay sending relay intro, so the RI DSM gets there first.
This makes relay faster and more reliable.
Periodically clean _nonceToAlice
Log tweaks

to use actual local IP rather than iterating through getCurrentAddresses(),
more efficient and works even when firewalled

containing a specific termination reason,
and create a post-termination handler directly from IES2 for any additional packets.
Don't do this unless we get intro key and validate static key in RI.
Don't blocklist the IP for a banned router unless we have validated
the static key to prevent spoofing.
Don't queue data packet after failure
Don't send additional terminations after receiving termination ack

Also removes the rebuildIfNecessary() call claimed to be removed in previous checkin.
Since we aren't thrashing any more, reschedule test after UNKNOWN results,
with the delay depending on current state.
log tweaks

to prevent thrashing.
Only rebuild in dropPeer() if the peer was a published introducer.
Only rebuild in addPeer() if the peer offered to relay and we need introducers.

to free up space and prevent problems handling additional packets

COWAL caused problems because replaceAddress() was removing the wrong address,
since RouterAddress.equals() does not compare caps, so empty '4' and '6' addresses would be equal.
So we could temporarily end up with multiple v4/v6 addresses.
COWAL wasn't really buying us anything anyway.

Fix removeAddress() that called the listener even if no change.

avoid dup previous charlies on list

blocklist IP if banned

Reduce transient blocklist sizes if slow
Improve logging of block source

Was setting packet length to number of packets.
Add check and log in UDPSender
Add notes where length is checked

reported by drzed

Fix wrong arguments order in ChaCha20 encrypt

See merge request i2p-hackers/i2p.i2p!72

Broken in 1.8.0. Almost certainly broke LS2 encrypted leaseset, but not yet tested.
Did not break anything else. I tested that this fix didn't break anything.

Add preliminary code to terminate session before
there are too many unacked messages to cause the IAE
(untested)
log tweaks

reported by drzed

and storing session request packet for retransmission
Previously, we would regenerate handshake state on every retry,
and we would not re-save the new session request packet after a retry.
Check for wrong token received in additional retries.