Pass OPTION_FORGIVING to VObject Reader

[solracsf]

See nextcloud/3rdparty#902

By passing the "forgiving" option, some ICS files that would otherwise be rejected, can be successfully imported.

Specifically, Outlook for Mac generates ICS files with an invalid key X-ENTOURAGE_UUID (underscore is invalid). By being forgiving, this key is ignored instead of rejected and I think a majority of calendar invitations from that client can now be processed successfully for NextCloud users. See issues nextcloud/server#16679 and nextcloud/server#17915 for more context.

I haven't seen other calls to VObject\Reader::read or VObject\Reader::readJson outside of validateICalendar where the same option should be passed, but it's possible I missed something.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.23%. Comparing base (a9d0a90) to head (4b8268b).
Report is 3 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1563      +/-   ##
============================================
- Coverage     97.24%   97.23%   -0.01%     
- Complexity     2834     2836       +2     
============================================
  Files           175      175              
  Lines          8843     9028     +185     
============================================
+ Hits           8599     8778     +179     
- Misses          244      250       +6     

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[phil-davis]

@solracsf can you add some unit test case(s) that demonstrate things that now pass?