Make it possible to turn text into link by selecting and pasting url over it

### What
When adding links to external URIs, I currently must wrap the label text with square brackets and add the link in parentheses afterwards, like this: `[label](example.org)`. This takes more time than being able to select text and paste the link in order to achieve the same thing.

### Why
I request this feature in order to save time on adding links to text.

### How
You can look at how this works in Github, Jira and Standardnotes for inspiration. Just highlight some text and paste a URL.

The issue names no files, tests, or entry points. Start by locating the editor's paste handling and existing Markdown link insertion behavior, using the GitHub, Jira, and Standard Notes examples for comparison; done means selecting text and pasting a URL turns that text into a link without manual Markdown syntax.

Written by the indexing model from the issue text.