Add DROPTIMEOUTS command

mikeperry kindly implemented a DROPTIMEOUTS command similar to the existing DROPGUARDS command but for dropping all computed circuit build timeouts:

https://github.com/mikeperry-tor/tor/commits/droptimeouts provides this functionality.

https://github.com/mikeperry-tor/torspec/commits/droptimeouts provides the spec.

I briefly ran commit 6ec01c5f of that branch (without the state file sync) in OnionPerf and can confirm that it works as expected. See OnionPerf's #33420 for details on that test run, if required.

It would be great to have this new command in Tor in order to run OnionPerf experiments where we periodically reset guards and timeouts and wait for new timeouts to be computed.

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