[helper] Filepath: Added accessibility helper method

Accessibility method helps identify whether a given save path directory is accessible for the user to write to.

meshroom/ui/components/filepath.py

@@ -57,6 +57,13 @@ def removeExtension(self, path):
         """ Returns the pathname without its extension (.ext)"""
         return os.path.splitext(self.asStr(path))[0]
 
+    @Slot(str, result=bool)
+    @Slot(QUrl, result=bool)
+    def accessible(self, path):
+        """ Returns whether a path is accessible for the user """
+        path = self.asStr(path)
+        return os.path.isdir(self.asStr(path)) and os.access(path, os.R_OK) and os.access(path, os.W_OK)
+
     @Slot(str, result=bool)
     @Slot(QUrl, result=bool)
     def isFile(self, path):