Add tags to the notifications

Reported by @holger.witsch

Is there a way to send tags and/or categories via the tango_* interface ?

For the tango_io, it is ready server-side but we would need to do something in the MetadataManager. Today the API looks like:https://icatplus.esrf.fr/api-docs/#/Logbook/post_logbook__sessionId__investigation_name__investigationName__instrument_name__instrumentName__event If you see the schema below the method it is ready to receive: 

"tags": [
    "string"
  ],

On the other hand the MetadataManager sends the event:https://gitlab.esrf.fr/icat/tango-metadata/-/blob/master/src/metadata_manager/MetadataManager.py#L630

{ 
"type" : eventType, 
"datasetName" : datasetName, 
"category" : category, 
"content" : content, 
"creationDate" : str(datetime.now().isoformat()) }

with no tags yet.

I think it would be enough to add:

{ 
"type" : eventType, 
"datasetName" : datasetName, 
"category" : category, 
"content" : content, 
"creationDate" : str(datetime.now().isoformat()) 
"tags" : ["Calibration", "Test", "Other tag"]
}

But then we need to change the MetadataManager API in order to receive the tags as parameters.

The current API is:

def notifyInfo(self, message):                
        self.sendNotification("notification", "info", message)

    def notifyDebug(self, message):                
        self.sendNotification("notification", "debug", message)

    def notifyCommand(self, message):                
        self.sendNotification("notification", "commandLine", message)

    def notifyError(self, message):                
        self.sendNotification("notification", "error", message)

    def userComment(self, message):                
        self.sendNotification("annotation", "comment", message)