[FIX] tools: prevent IoT crash due to missing library

Before this commit:
Any IoT-box syncing to a version 16 (and >) database would not be
able to start odoo service due to the `num2words` missing library.

This is in practice the fault of the IoT as this library is part
of odoo requirement. But to solve it it would need to recreate an
IoT box OS image and asking customers to re-flash their SD card
which is not convenient and time consumming.

After this commit:
Import conditionally num2words

opw-3902183

closes #165067

Signed-off-by: Pierre Masereel (pim) <pim@odoo.com>

odoo/tools/_monkeypatches.py

@@ -1,14 +1,19 @@
 import ast
 import os
 import logging
-import num2words
 from odoo import MIN_PY_VERSION
-from .num2words_patch import Num2Word_AR_Fixed
 from shutil import copyfileobj
 from types import CodeType
 
 _logger = logging.getLogger(__name__)
 
+try:
+    import num2words
+    from .num2words_patch import Num2Word_AR_Fixed
+except ImportError:
+    _logger.warning("num2words is not available, Arabic number to words conversion will not work")
+    num2words = None
+
 from werkzeug.datastructures import FileStorage
 from werkzeug.routing import Rule
 from werkzeug.wrappers import Request, Response
@@ -72,4 +77,5 @@ def literal_eval(expr):
 if MIN_PY_VERSION >= (3, 12):
     raise RuntimeError("The num2words monkey patch is obsolete. Bump the version of the library to the latest available in the official package repository, if it hasn't already been done, and remove the patch.")
 
-num2words.CONVERTER_CLASSES["ar"] = Num2Word_AR_Fixed()
+if num2words:
+    num2words.CONVERTER_CLASSES["ar"] = Num2Word_AR_Fixed()