Nice to have: Option to keep English original keywords as valid

When we have translated keywords and the original English keywords, the test run would fail because the English keywords are unknown.
Would be nice to have an option to make this current behavior as a strict mode, and have the option to allow mixed translation and English keywords the default.

For example:

mode=multi   # The default (or mixed)

or

mode=strict   # The exact translation (or single) (or exact) ....

Copy of https://github.com/MarketSquare/robotframework-seleniumlibrary-translation/issues/59 because it also needs support from PLC.

未指定檔案或測試。首先追蹤 PythonLibCore 如何驗證已翻譯的關鍵字，以及如何公開設定選項，然後查看 github.com/MarketSquare/robotframework-seleniumlibrary-translation/issues/59 中相關的翻譯 issue。完成的標準是：預設接受混合使用的已翻譯關鍵字和英文關鍵字，同時嚴格模式繼續拒絕英文關鍵字。