Paste URL in Markdown automatically create link

Implementation Guide

We already do something similar to this in the plain text editor when you select text and press the "Add a link" toolbar button - it replaces the text with a markdown link syntax with the selected text in the "text" portion and the cursor is placed in the "url" section.

The rich text editor does already support selecting text and when pasting a url, creates a link.

I believe we could modify/enhance the code at https://gitlab.com/gitlab-org/gitlab/blob/master/app/assets/javascripts/lib/utils/text_markdown.js#L293-L308 in order to achieve this. Tests would go into https://gitlab.com/gitlab-org/gitlab/blob/master/spec/frontend/lib/utils/text_markdown_spec.js

Problem to Solve

When adding inline hyperlinks in Markdown users must select the text, press the hyperlink button and then go back to the URL area and paste it in. Alternatively users must remember markdown syntax as they type and add the appropriate structure to add an inline link to their text.

Additional Details

When using the Message box in Slack, it's possible to highlight text, press cmd+V and have the highlighted text automatically converted to a hyperlink in the message.

Proposal

When editing Markdown across GitLab, either in Issues, Editors (Static Site, Web IDE) or other places, it should be possible to highlight text and have the link structure automatically applied if the pasted content is detected to be a hyperlink.