- Added a link in the sidebar to clone a modpack.
- Cloning to an existing modpack will overwrite it with the source's packs.
- Cloning to a nonexistent pack will create it.

Some concerns:
- There are no permissions associated with cloning.
- Destination list is loaded via JS therefore the modpacks have to be public even if the user has access to them.
- No modpack permissions are considered before handling cloning to/from anything.

- Clone inputs are validated and required.
- Fixed issue where min_memory wasn't actually being copied.
- Fixed issue where cloned builds weren't also cloning modversions.
- Removed using AJAX to get the list of destinations.
- Added validation condition to ensure cloning to the same modpack doesn't happen.
- Removed the ability to create entries for the source selector. (This was meant for debugging only.)