Sync frontend en-GB.lib_joomla.ini with changes made in backend.

[Bakual]

The en-GB.lib_joomla.ini in frontend is out of sync with the same file in backend.
until now, they were identical and translators could just copy-paste it.
Thanks to @imanickam to catch that.

This PR copies the content from the backend file to the frontend file.
Main difference is the added strings from #7637:

JLIB_HTML_BATCH_MOVE_QUESTION="Do you want to move the items or make a copy of them?"
JLIB_HTML_BATCH_NO_CATEGORY="- Don't move or copy -"

However there are a lot of punctuation changes which are most likely coming from #5615. From what I see there were some changes in that PR which only were did in one of the two files.
I need input here which changes are correct and which should be reverted and thus be fixed in the backend file. @brianteeman can you look over it?

[Bakual]

Updated with corrections by @brianteeman (Thanks!)

[infograf768]

I suggest to merge this asap and let it know to TTs (mainly the 2 new strings).

[Bakual]

I'll check with @imanickam if he wants them merged now or for 3.4.5.
The new strings are already present in the backend and not used in frontend. So there is no hurry to merge it.

[infograf768]

@Bakual
Some TTs have only a frontend lib_joomla.ini and therefore it has to be told to them or they will not get the 2 new strings.

[infograf768]

This is for packs who have only a limited backend inis:
See:

https://docs.joomla.org/J3.x:Making_a_Language_Pack_for_Joomla#The_Site-only_pack

[infograf768]

forget it, it can wait if judged necessary. as in admin is loaded only the admin file.

[Bakual]

Merged after chatting with @imanickam