Set replicas to panic on disk errors, and optionally panic on replication errors (#10504)

* Till now, replicas that were unable to persist, would still execute the commands
  they got from the master, now they'll panic by default, and we add a new
  `replica-ignore-disk-errors` config to change that.
* Till now, when a command failed on a replica or AOF-loading, it only logged a
  warning and a stat, we add a new `propagation-error-behavior` config to allow
  panicking in that state (may become the default one day)

Note that commands that fail on the replica can either indicate a bug that could
cause data inconsistency between the replica and the master, or they could be
in some cases (specifically in previous versions), a result of a command (e.g. EVAL)
that failed on the master, but still had to be propagated to fail on the replica as well.

src/debug.c

@@ -416,6 +416,8 @@ void debugCommand(client *c) {
 "    Like HTSTATS but for the hash table stored at <key>'s value.",
 "LOADAOF",
 "    Flush the AOF buffers on disk and reload the AOF in memory.",
+"REPLICATE <string>",
+"    Replicates the provided string to replicas, allowing data divergence.",
 #ifdef USE_JEMALLOC
 "MALLCTL <key> [<val>]",
 "    Get or set a malloc tuning integer.",
@@ -849,6 +851,10 @@ NULL
     {
         server.aof_flush_sleep = atoi(c->argv[2]->ptr);
         addReply(c,shared.ok);
+    } else if (!strcasecmp(c->argv[1]->ptr,"replicate") && c->argc >= 3) {
+        replicationFeedSlaves(server.slaves, server.slaveseldb,
+                c->argv + 2, c->argc - 2);
+        addReply(c,shared.ok);
     } else if (!strcasecmp(c->argv[1]->ptr,"error") && c->argc == 3) {
         sds errstr = sdsnewlen("-",1);