[3.x] mod_wrapper. Add HTML5 mode without B\C break

[ReLater]

Related to #19965
See discussion there concerning B\C breaks in Joomla 3.x.

Summary of Changes

• Adds a new switch Legacy (HTML4) versus HTML5.
• Legacy is the default setting. Thus, this pr will not break older template overrides that use HTML4 attributes for IFRAME tags that have been removed in HTML5.
• HTML5 uses CSS style instead.
• Doesn't touch old parameter types and names but translates them via PHP for HTML5 mode if necessary.
• Comment: Because most current browsers don't support CSS rule overflow for displaying/hiding scroll bars for IFRAME tags scrolling attribute cannot be removed in HTML5 mode.

Testing Instructions

Testing Instructions

• Apply patch.
• Create a module of type "Wrapper" with setting Mode = Legacy.
• Create another module of type "Wrapper" with setting Mode = HTML5.
• Compare outputs in frontend.
• Test also other settings and compare output in frontend.

Expected result

• No optical difference

Documentation Changes Required

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