Add "New Project" command

[adam-coster]

We frequently need to create one-off projects for replicating bugs and related tasks. Doing this from the Stitch VSCode extension would be particularly helpful.

Base features we need:

• Base it off of the current project (so no ability to add fully from scratch)
• Choose the location
• Choose the project name
• Use its yyp of the current project as the template
• Create the minimal file setup needed to make a new project, stripping out everything from the template YYP
• Add a default room rm_init
• Add a default object o_init
• Add o_init to rm_init
• Open the project in a new VSCode window

[adam-coster]

Added in v1.67.0