Investigate if square size can be added as a parameter to `TreeConstructorFn`

[rootulp]

Prerequisite

1. https://github.com/celestiaorg/rsmt2d/issues/248

Context

https://github.com/celestiaorg/rsmt2d/blob/76d744060bc715801cd9e01119bfb1dea00dc488/tree.go#L9-L11 lacks a parameter for square size so multiple tree constructor functions must be registered (one per square size).

Proposal

Explore if it's possible to add a square size param to the tree constructor function.