Move to file action

[Jarred-Sumner]

It would be really nice if there was a "move this struct to a new file" LSP action that becomes available when you select const Foo = struct {.... This would involve:

• Copying all the referenced identifiers as imports in the new file
• Adding pub in front of referenced identifiers and functions that are not public
• Adding a pub const Foo = @import("./${target}.zig")

This is a feature that the TypeScript LSP has (when you click "Refactor")

When you click "Move to file", it causes the editor to prompt the user for a file path