Add issue remote link

[IncandescentChrysalis]

Adding a link to an application connected with a Jira instance through the /rest/api/2/issue/{issueIdOrKey}/remotelink Jira API route, an application section might be provided.
This might for instance be used to add Confluence links to a connected Confluence instance.
Cf. Atlassian knowledge base about the different kind of links.

[gonchik]

@IncandescentChrysalis do you have a plan to continue ? :)

[IncandescentChrysalis]

@IncandescentChrysalis do you have a plan to continue ? :)

Writing a new set of tests was not trivial: I would have gladly welcomed help…
The code was fine all along, it was merely tests blocking the feature.

Heck, there was not previous test for that create_or_update_issue_remote_links method, despite code already existing! I added one.