Add support for custom provider implementation

- Add a set_provider_factory() method to server_state to allow
  injecting provider factory which will be called when the
  provider is loaded.

Other related changes:
- Implement to_string() helper method for id class.
- Fix id ostream operator human readable id printing.
- Pass victim client_service as an argument to provider::bf_abort()
  to allow passing victim context to custom provider.
- Implement prev() helper method for seqno class.
- Make server_state recover_streaming_appliers_if_not_recovered()
  public. In some recovery scenarios the method must be called outside
  of server_state internal code paths.
- Add storage_service requires_globals() method. The storage service
  implementation may override this to return false if changing to
  storage service context does not require store/reset globals.
- Change view final() to also require that the view status is not
  primary for the view to be final. Also change the method name to
  is_final() to avoid confusion with C++ final identifier.
- Fixes to server state handling in disconnecting and disconnected
  states.
- Keep TOI meta data over whole TOI critical section.

Co-authored-by: Denis Protivensky <denis.protivensky@galeracluster.com>

test/test_utils.cpp

@@ -41,11 +41,12 @@ void wsrep_test::bf_abort_in_total_order(wsrep::client_state& cc)
 }
 // BF abort method to abort transactions via provider
 void wsrep_test::bf_abort_provider(wsrep::mock_server_state& sc,
-                                   const wsrep::transaction& tc,
+                                   const wsrep::client_state& victim_cs,
                                    wsrep::seqno bf_seqno)
 {
     wsrep::seqno victim_seqno;
-    sc.provider().bf_abort(bf_seqno, tc.id(), victim_seqno);
+    sc.provider().bf_abort(bf_seqno, victim_cs.transaction().id(), victim_cs.client_service(),
+                           victim_seqno);
     (void)victim_seqno;
 }
 
@@ -63,13 +64,10 @@ void wsrep_test::terminate_streaming_applier(
     mc.before_command();
     wsrep::mock_high_priority_service hps(sc, &mc, false);
     wsrep::ws_handle ws_handle(transaction_id, (void*)(1));
-    wsrep::ws_meta ws_meta(wsrep::gtid(wsrep::id("cluster1"),
-                                       wsrep::seqno(100)),
-                           wsrep::stid(server_id,
-                                       transaction_id,
-                                       wsrep::client_id(1)),
-                           wsrep::seqno(0),
-                           wsrep::provider::flag::rollback);
+    wsrep::ws_meta ws_meta(
+        wsrep::gtid(wsrep::id("cluster1"), wsrep::seqno(100)),
+        wsrep::stid(server_id, transaction_id, wsrep::client_id(1)),
+        wsrep::seqno(0), wsrep::provider::flag::rollback);
     wsrep::const_buffer data(0, 0);
     sc.on_apply(hps, ws_handle, ws_meta, data);
 }