fix(export): remove new lines from form title in the exported filename

[tcitworld]

See #1758 (comment)

Even though new lines are valid POSIX, let's avoid them (because it seems Nextcloud Files really doesn't like them in filenames).

[codecov]

Codecov Report

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Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2343   +/-   ##
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  Coverage        ?   35.62%           
  Complexity      ?     1028           
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  Files           ?       71           
  Lines           ?     3882           
  Branches        ?        0           
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  Hits            ?     1383           
  Misses          ?     2499           
  Partials        ?        0           

[Chartman123]

Great, thank you :)

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