Risks of having no limit on arena `bulkCreate` planets

[cha0sg0d]

This is ok for now, but in the future I think we need to set a cap on bulkCreate due to gas limit. With a quick test, gas is just under 500,000 per planet created. So with a block limit of 15,000,000, this gives us max 30 planets that can be created. We need to enforce this client side, otherwise users will face Exceeds block gas limit error and waste all of their funds.

[0xhank]

this function is currently not being used anywhere, I added it as a utility function if we wanted to use it down the line. So we can either leave it out or update it later