add basic test for TSIG key dump/restore functionality

stop and restart the server in the 'tsiggss' test, in order
to confirm that GSS negotiated TSIG keys are saved and restored
when named loads.

added logging to dns_tsigkey_createfromkey() to indicate whether
a key has been statically configured, generated via GSS negotiation,
or restored from a file.

fuzz/dns_message_checksig.c

@@ -263,8 +263,8 @@ LLVMFuzzerInitialize(int *argc __attribute__((unused)),
 	}
 
 	result = dns_tsigkey_create(name, dns_tsig_hmacsha256_name, secret,
-				    sizeof(secret), false, NULL, 0, 0, mctx,
-				    ring, &tsigkey);
+				    sizeof(secret), false, false, NULL, 0, 0,
+				    mctx, ring, &tsigkey);
 	if (result != ISC_R_SUCCESS) {
 		fprintf(stderr, "dns_tsigkey_create failed: %s\n",
 			isc_result_totext(result));