Adding --same-key and --tcp flags to the client (needed a bug fix)

[sbocconi]

Changes

1. Added a --same-key flag to sig0lease-client (main/cmd/sig0lease-client/main.go) for both register and refresh. When passed, it builds the KEY RR straight from the already-loaded signing key (factored out into a shared keyRRFromClientKey helper, reused by the existing additional-section logic) and adds it to the Update section — so the same key no longer needs to be retyped as a full rr-spec string.

   • It composes with --signer=: with the default auto it's recognized as already present (no duplicate Additional copy); it satisfies --signer=update's requirement automatically; and it correctly errors if combined with --signer=none or with a conflicting explicit KEY rr-spec for the same name. Help text and usage examples were updated

2. Added --tcp (bare boolean, same style as --same-key) to register/refresh/register-tamper and verify. extractTCPFlag/queryProtocol pick "tcp" vs the default "udp", both client.New(...) call sites now use it, and help text/usage lines were updated (including fixing verify's doc, which listed a stale unused second positional arg).

Testing the client over TCP revealed a bug in handling TCP connections in miekg/dns

3. server/server.go: replaced serveTCP's reliance on dns.Server.ListenAndServe() with a custom accept loop mirroring serveUDP (manual 2-byte-length-prefix framing, one unconditional full Unpack(), same acceptMsg accept/reject policy, same reject-response handling).

Added TCP functionality to the test script:

4. Added PROXY_PROTOCOL="${PROXY_PROTOCOL:-udp}" to tests/utils.sh with default-unless-overridden mechanism. run_client in tests/test_update.sh now appends --tcp to every client invocation when PROXY_PROTOCOL=tcp, so the entire existing suite (every register/refresh call, ~25 call sites) runs over TCP with PROXY_PROTOCOL=tcp tests/test_update.sh, with no per-call-site changes needed.

[sbocconi]

This last PR modifies some of the changes introduced by the previous one, because of an unexpected bug in miekg/dns library resulting in the fact that that TCP listener cannot be used (this was not known when making the previous PR).

[adam-burns]

Changes

1. Added a --same-key flag to sig0lease-client (main/cmd/sig0lease-client/main.go) for both register and refresh. When passed, it builds the KEY RR straight from the already-loaded signing key (factored out into a shared keyRRFromClientKey helper, reused by the existing additional-section logic) and adds it to the Update section — so the same key no longer needs to be retyped as a full rr-spec string.

I'd propose reversing the behaviour so the default is --same-key, because this is what normally happens in register and enable an option for specifying another key. Thoughts?