Add new `Balance.Size.{Coin,TokenBundle,Selection}` module hierarchy

[Anviking]

• Move distributeSurplus to new Balance.Size.Coin module
• Balance.TokenBundleSize -> Balance.Size.TokenBundle
• SizeEstimation -> Balance.Size.Selection

Comments

Even if this is not the module structure we ultimate want, I thought this would be a step in the right direction

Issue Number

None / preparation for ADP-3347 in particular by making the Balance module smaller

[Anviking]

Not ruling this idea out, but closing for now.