MM-9547 Added config setting to control url autolinking schemes (#8862)

* MM-9547 Added config setting to control autolinking schemes

* Renamed AutolinkingSchemes to CustomUrlSchemes

config/default.json

@@ -97,6 +97,7 @@
         "ExperimentalPrimaryTeam": ""
     },
     "DisplaySettings": {
+        "CustomUrlSchemes": [],
         "ExperimentalTimezone": false
     },
     "ClientRequirements": {