feat(config): move Fevm.Events->Events, implement soft deprecation

Closes: https://github.com/filecoin-project/lotus/issues/11679

* Introduce a `moved:"To.New.Config"` tag which prints a stderr warning when
  you use one of these, but will move any set value to the new location if the
	new location isn't already set itself.
* Look for `X is DEPRECATED` to hold certain fields back from documentation.
* Use `toml:"omitempty"` to prevent the default config output from having these
  deprecated values.

itests/kit/node_opts.go

@@ -65,7 +65,7 @@ var DefaultNodeOpts = nodeOpts{
 			// test defaults
 
 			cfg.Fevm.EnableEthRPC = true
-			cfg.Fevm.Events.MaxFilterHeightRange = math.MaxInt64
+			cfg.Events.MaxFilterHeightRange = math.MaxInt64
 			cfg.Events.EnableActorEventsAPI = true
 			return nil
 		},