Add-JiraRemoteLink Allows Adding Remote Links

Picket the "patch zip" from #375 and created a extended version and a pull request.

Description

This adds the Add-JiraRemoteLink function from #375 in a massive extended version. Due the original one only allowed url and txt attribute, I used the format defined by Get-JiraRemoteLink. For that I also created a ConvertFrom-JiraLink as counterpart to the existing ConvertTo-JiraLink.

Motivation and Context

I do not understand why there was a format change of the incoming JSON, as done in Get-JiraRemoteLink, in this case useful anyway but that's an other discussion and I wanted the change to be compatible to the existing stuff as possible.

As the previous discussed original, this only allows adding additional remote links, which is also reflected in the naming of the function. For that the function verifies that there is no Id or RestUrl in the object, because that would only make sense for updating existing remote links and could confuse the user of this function.

Types of changes

[ ] Bug fix (non-breaking change which fixes an issue)
[X] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist

[ ] My code follows the code style of this project.
[ ] I have added Pester Tests that describe what my changes should do.
[ ] I have updated the documentation accordingly.

AtlassianPS / JiraPS