[EXTERNAL USER][ISSUE] - Allow External Share user to create issue

Description

Currently external users are unable to create issues and are limited to editing existing issues.

Suggested improvement

Enable external users to create issues using external share interface

Decision on implementation
Creation will be possible from board share. For starters, no additional share will be created for every new issue, created issue will be accessed through board share (configuring the board so that new issues are on it is responsibility of the client). Only basic data can be set during creation, but more can be added afterwards during edition (provided that edition is turned on in configuration).

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Based on following client requests:

https://ossapps.atlassian.net/browse/SUP-3181

https://ossapps.atlassian.net/browse/SUP-5008

https://ossapps.atlassian.net/browse/SUP-5108

https://ossapps.atlassian.net/browse/SUP-5406

https://ossapps.atlassian.net/browse/SUP-5752

Linked issues

relates to
Issue Type Icon ESFJ-466 The "Code wrap" feature lacks a background when being edited using the issue creation editor Priority: Medium Assignee:
Withdrawn
Issue Type Icon ESFJ-469 The link option in the editor is not dark mode friendly and includes "Link target" which is an unnecessary tab Priority: Low Assignee:
Released