Improvement of error responses from the API

We need to respond with proper error codes and messages.

Example scenarios:

404 if the resource is not found (e.g. faulty character name)
429 if the request is being throttled (tibia code is actually 403)
503 if there was some upstream issue
and also something when tibia is having maintenance.

Section that needs to be rewritten/enhanced:

Lines 679 to 691 in ce26e50

    
           func tibiaDataRequestHandler(c *gin.Context, tibiaDataRequest TibiadataRequestStruct, requestHandler func(string) (interface{}, int), handlerName string) { 
        
           	BoxContentHTML, err := TibiadataHTMLDataCollectorV3(tibiaDataRequest) 
        
           	// return error (e.g. for maintenance mode) 
        
           	if err != nil { 
        
           		TibiaDataAPIHandleResponse(c, http.StatusBadGateway, handlerName, gin.H{"error": err.Error()}) 
        
           	} 
        
           	jsonData, httpStatusCode := requestHandler(BoxContentHTML) 
        
           	// return jsonData 
        
           	TibiaDataAPIHandleResponse(c, httpStatusCode, handlerName, jsonData) 
        
           }

This should then also be added to the documentation annotation, so that docs get automatic update too.

Separate branch (feature-error-handling) created for this.

error handling implemented by #86, closing issue.

	func tibiaDataRequestHandler(c *gin.Context, tibiaDataRequest TibiadataRequestStruct, requestHandler func(string) (interface{}, int), handlerName string) {
	BoxContentHTML, err := TibiadataHTMLDataCollectorV3(tibiaDataRequest)

	// return error (e.g. for maintenance mode)
	if err != nil {
	TibiaDataAPIHandleResponse(c, http.StatusBadGateway, handlerName, gin.H{"error": err.Error()})
	}

	jsonData, httpStatusCode := requestHandler(BoxContentHTML)

	// return jsonData
	TibiaDataAPIHandleResponse(c, httpStatusCode, handlerName, jsonData)
	}