Update context to have a generic method.

Add a generic method `GetAs` to get request data.

context.go

@@ -265,6 +265,20 @@ func (c *Context) Get(key string) (value any, exists bool) {
 	return
 }
 
+// GetAs returns the value for the given key, ie: (value, true).
+// If the value does not exist it returns (nil, false)
+func (c *Context) GetAs[T any](key string) (result T, exists bool) {
+	c.mu.RLock()
+	value, exists := c.Keys[key]
+	c.mu.RUnlock()
+	
+	if !exists {
+	   return	
+	}	
+	result, exists = value.(T)
+	return
+}
+
 // MustGet returns the value for the given key if it exists, otherwise it panics.
 func (c *Context) MustGet(key string) any {
 	if value, exists := c.Get(key); exists {