Feature: Add template support when using `Make current document folder note`

[zhelding]

When converting an existing standard note to a folder note, I currently have to manually insert the contents of the folder note template.

It would be very helpful to have an option to append the folder note template to the end of an existing note when converting it.

Alternatively: the folder note template option could add support for a placeholder like {{EXISTING_CONTENT}} -- which would allow for custom placement of the original note's content in the larger template.