GetWordsInString Method Changes

[hylstonnb]

Fixes issues when text containing HTML tags are provided, causing failures under the spell check.

• Html tags should now be removed from the list of words (result of the method getWordsInString), as they shouldn't be considered as words for spell checks.
• The method getWordsInString returns an empty array if a null or empty string is provided as input.
• Added unit tests for the getWordsInString method

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