Sending bug and crash reports to the helpdesk

[mXaln]

Fixes #336.

Changes in this pull request:

• Added optional email field (Crash screen, feedback dialog) if users want to be contacted regarding their issues.
• Removed the ability to upload to GitHub issues

[gitguardian]

️✅ There are no secrets present in this pull request anymore.

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While these secrets were previously flagged, we no longer have a reference to the
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Find here more information about risks.

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