Extract "state-watching" etcd client into a separate file

pg_states.cpp

@@ -0,0 +1,33 @@
+#include "pg_states.h"
+
+const int pg_state_bit_count = 13;
+
+const int pg_state_bits[13] = {
+    PG_STARTING,
+    PG_PEERING,
+    PG_INCOMPLETE,
+    PG_ACTIVE,
+    PG_STOPPING,
+    PG_OFFLINE,
+    PG_DEGRADED,
+    PG_HAS_INCOMPLETE,
+    PG_HAS_DEGRADED,
+    PG_HAS_MISPLACED,
+    PG_HAS_UNCLEAN,
+    PG_LEFT_ON_DEAD,
+};
+
+const char *pg_state_names[13] = {
+    "starting",
+    "peering",
+    "incomplete",
+    "active",
+    "stopping",
+    "offline",
+    "degraded",
+    "has_incomplete",
+    "has_degraded",
+    "has_misplaced",
+    "has_unclean",
+    "left_on_dead",
+};