Default to signing over all relevant square sizes when creating a WirePayForMessage

[evan-forbes]

Currently we require a user to select which square sizes they want to sign over. This is a hostile UX, as the user must have extraneous knowledge on the data square, malleated transactions, and the non-interactive default rules to know which square sizes to sign over. For most cases, the user will likely want to sign all relevant square sizes.

as pointed out in #236, this does not mean that they have to sign over all square sizes

if a message can fit on a single row of square size x, then a valid commitment for square size x is valid for all square sizes >= x.

Also, they don't have to sign over square sizes that don't have enough shares to include their message + MsgPayForMessage transaction.

[toanngosy]

Hi @evan-forbes, can I work on this?

[evan-forbes]

certainly!