feat: add toString implementation (#73)

this is a partial revert of cf485d2 where toString was removed from
ignition.common.i18n
ignition.common.sqltags.model.types

Refs: cf485d2

Author: César Román

src/com/inductiveautomation/ignition/common/i18n/__init__.py

@@ -43,3 +43,7 @@ def setKey(self, key):
     def setParams(self, params):
         # type: (List[Object]) -> None
         pass
+
+    def toString(self, locale=None):
+        # type: (Optional[Locale]) -> String
+        pass

src/com/inductiveautomation/ignition/common/sqltags/model/types/__init__.py

@@ -55,6 +55,10 @@ def isOpcBadData(self):
         # type: () -> bool
         pass
 
+    def toString(self, locale=None):
+        # type: (Optional[Locale]) -> String
+        pass
+
     @staticmethod
     def valueOf(name):
         # type: (str) -> DataQuality

src/org/json/__init__.py

@@ -99,6 +99,10 @@ def toJSONObject(self, names):
         # type: (JSONArray) -> JSONObject
         pass
 
+    def toString(self, indentFactor=None):
+        # type: (Optional[int]) -> String
+        pass
+
     def write(self, writer):
         # type: (Writer) -> Writer
         pass
@@ -256,6 +260,10 @@ def toJSONArray(self, names):
         # type: (JSONArray) -> JSONArray
         pass
 
+    def toString(self, indentFactor=None):
+        # type: (Optional[int]) -> String
+        pass
+
     @staticmethod
     def valueToString(value):
         # type: (Object) -> String