Support creating new file from URL in the Web IDE

The Web IDE supports creating new files by using the new file button in the UI, but it is very helpful to be able to craft a URL that will open the web ide and create the file. This will allow an empty repo to have a link to Add README with a single click.

This capability is necessary to replace the ACE editor with the Web IDE.

Proposal

If the Web IDE is opened with a URL to a file that doesn't exist the Web IDE should create an empty file ready for editing.

https://gitlab.com/-/ide/project/<group>/<project>/edit/<branch>/-/<file>

This will allow the URLs on the empty repo state to be updated:

• Add README - open the Web IDE with an empty README file
• Add CHANGELOG - open the Web IDE with an empty CHANGELOG file
• Add CONTRIBUTING - open the Web IDE with an empty CONTRIBUTING file

Links / references