Add a func to determine if Data is the minimum square

[evan-forbes]

celestia-node checks if the data will result in an empty square, which has a deterministic data root. We should add a function that determines that here so that they don't have to think about that logic.

[rootulp]

Is this effectively moving https://github.com/celestiaorg/celestia-node/blob/94cd2a6664a24336629caf12b7560cc7cb353f6e/share/empty.go#L62-L65 to an exported function in celestia-app?

[evan-forbes]

this should just be a simple method that return true or false depending on if the data square is empty, so we're not creating a new square like the function above

[rootulp]

I think celestia-node intentionally creates an empty ODS for caching so we could move logic from https://github.com/celestiaorg/celestia-node/blob/94cd2a6664a24336629caf12b7560cc7cb353f6e/share/empty.go#L24-L34 to celestia-app but what about https://github.com/rootulp/celestia-node/blob/18117b7eb58e7a1e6805123fa33aef296b1783c2/share/empty.go#L54-L55

[evan-forbes]

ahh I see, then I guess the easiest is to do what suggested by only implementing emptyDAH. Perhaps we could do both. Anything we can do to keep logic in the app that we are responsible for maintaining and not celestia-node