GO Contact Sync Mod Code

- added debug log to RemoveGoogleDuplicatedContacts (e.g. to investigate root cause for https://sourceforge.net/p/googlesyncmod/support-requests/834/)
- added more debug info to UpdateRecurrence to investigate root cause for https://sourceforge.net/p/googlesyncmod/bugs/1280/

- fixed bug: https://sourceforge.net/p/googlesyncmod/bugs/1286/

- updated to new Nuget packages
- fixed some minor bugs

- fixed: keep appointment private, if synchronized back with PrivateSetting=true

- changed update message label text
- comment out unused code for using own client secrets file
- HttpClient use only TLS 1.2 for update checks
- creating release zip file (portable version of gcsm) for installer project

- fixed bug #825 object reference error
- replaced several unnecessary usages of nullable ContactPropertiesUtils.Get...

- fixed bugs #1278 object reference error
- added Utc2Local conversion for all dates

- fixed several Google People API issues, e.g. converted person LastUpdate from UTC to localTime
- fixed support request #823 - Contact group name "Starred in Android" is a reserved legacy name. Please use the system "contactGroups/starred" group instead. [400]