capitalizeAllWordsFirstLetter() method to capitalize only first letter in String words

[anasfik]

turn the first letter only of words in a String to uppercase(), tested it with examples

capitalizeAllWordsFirstLetter() will turn the first letter of words to upper case and the rest to lower case, useful in cases of writing titles of screens, articles titles, buttons and ad banners...

Every PR must update the corresponding documentation in the code, and also the readme in English with the following changes.

Pre-launch Checklist

• [x] I updated/added relevant documentation (doc comments with ///).
• [x] I added new tests to check the change I am making or feature I am adding, or @jonataslaw said the PR is test-exempt.
• [x] All existing and new tests are passing.