Replace deprecated styleWithSpan with styleWithCSS

[lqez]

What does this PR do?

• Once upon a time (lol), we'd had an option styleWithSpan which affects on styleWithCss of execCommand. I don't know when and why we removed this option.
• styleWithSpan could be confused with styleWithCSS so I renamed it as same as its property name of content editable.

How should this be manually tested?

• Set styleWithCSS as true or false. And apply a format to text.

What are the relevant tickets?

• Correction for styleWithSpan setting #727
• Lost styleWithSpan option #3025
• Hi, we are having issue when user try to use span. It increses text font size. I tried to play with styleWithSpan. Made it true but didn't work. Any possible solution? #2643

Checklist

• added relevant tests
• didn't break anything

[lqez]

Thank you so much @easylogic