[CSM] Add flavour limits controlled by server (#5930)

* [CSM] Add flavour limits controlled by server

Server send flavour limits to client permitting to disable or limit some Lua calls

* Add limits for reading nodedefs and itemdefs

* flavour: Add lookup node limits

* Merge get_node_or_nil into get_node.

Sending fake node doesn't make sense in CSM, just return nil if node is not available for any reason

* Add node range customization when noderange flavour is enabled (default 8 nodes)

* Limit nodes range & disable chat message sending by default

* Bump protocol version

doc/client_lua_api.md

@@ -701,12 +701,10 @@ Call these functions only at load time!
     * Returns the time of day: `0` for midnight, `0.5` for midday
 
 ### Map
-* `minetest.get_node(pos)`
-    * Returns the node at the given position as table in the format
-      `{name="node_name", param1=0, param2=0}`, returns `{name="ignore", param1=0, param2=0}`
-      for unloaded areas.
 * `minetest.get_node_or_nil(pos)`
-    * Same as `get_node` but returns `nil` for unloaded areas.
+    * Returns the node at the given position as table in the format
+      `{name="node_name", param1=0, param2=0}`, returns `nil`
+      for unloaded areas or flavour limited areas.
 * `minetest.find_node_near(pos, radius, nodenames, [search_center])`: returns pos or `nil`
     * `radius`: using a maximum metric
     * `nodenames`: e.g. `{"ignore", "group:tree"}` or `"default:dirt"`