[FR] Change file extension of existing file using a command

[holroy]

I would love for a command to change the file extension to whichever extension you've already entered in the settings.

This would make it a whole lot easier to create for example javascript files from within Obsidian, as you could create a new note, trigger the command and select the appropriate file extension.

I first described this idea here: #7 (comment)

Having a command like Plaintext: Change extension of file, would allow it to be added to stuff like the keyboard hotbar, or accessed through the command palette, and so on.