[plg_content_vote|pagebreak] Load language files only when needed

[andrepereiradasilva]

Pull Request for Issue #11714 (part 2).

Summary of Changes

Only load the plg_content_pagebreak and plg_content_vote languages files when they are needed.
Example: don't load them if the show_vote is not active or there is no pagebreak class.

For more info see #11714

Testing Instructions

Reproduce

• Use latest staging
• Enable plugin content vote and plugin content pagebreak
• Enable debug and debug lang in global config
• Enable debug system plugin with all options activated
• Go to frontend and check the debug console
• Notice JROOT/administrator/language/en-GB/en-GB.plg_content_vote.ini and JROOT/administrator/language/en-GB/en-GB.plg_content_pagebreak.ini language file is loaded no matter what page you are (even in backend pages they are loaded).

Test patch

• Apply patch
• Repeat the steps above and checkthe two language files are NOT loaded (except when needed).
• Check plugin work as before if language files are required to load (ex: show_vote enabled / article with pagebreak, etc).

Documentation Changes Required

None.

[andrepereiradasilva]

@mbabker i updated this PR to follow the logic you added for modules in #11698, but this time for the plugins.

Can you check if all ok?

[mbabker]

Looks fine.

[andrepereiradasilva]

thanks

[alikon]

I have tested this item ✅ successfully on 3b028a3

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_{This comment was created with the J!Tracker Application at issues.joomla.org/joomla-cms/11730.}

[jeckodevelopment]

I have tested this item ✅ successfully on 3b028a3

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_{This comment was created with the J!Tracker Application at issues.joomla.org/joomla-cms/11730.}

[jeckodevelopment]

RTC

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_{This comment was created with the J!Tracker Application at issues.joomla.org/joomla-cms/11730.}