Rojo should have a command to 'patch' an existing Roblox file using a Rojo project

[Dekkonot]

It's often desirable to just apply a specific change to a Roblox file using a Rojo project; this can be done manually by just opening the file in Roblox Studio, syncing with Rojo, and then saving the file, but it's not possible to do it programmatically.

It's possible to replicate this using Lune or some other tool, but we can make it easier by just including a command in Rojo to apply a patch to a provided Roblox file. This would mean that it's possible to use Rojo specific middleware for generating patches, and I think it'd be helpful for the overall ecosystem and facilitate using Rojo as a build tool.