Move default values for blob params to appconsts module

[rahulghangas]

Summary

Default values for blob params are currently hardcoded and should be moved to appconsts module

[rootulp]

Naive question but why do we want to define these default parameters in the appconsts module if the associated parameter is configured in the blob module?

I assume the end-goal is that the defaults are only used to set the initial value of the parameter in the blob module and after that the parameters are subject to modification through governance. The value that should be used throughout the application is therefore the parameter in the blob module not the default in appconsts.

[rahulghangas]

This was done because I wanted to do the changes incrementally (since it's going to break app in a few different places). PR resolving #1032 will replace all usages of default values to paramstore reads

[rootulp]

I don't follow why this issue is desirable as an incremental step. If the MaxSquareSize param is defined in the blob module, then I would expect the initial value (i.e the default) for this parameter to also be defined in the blob module.

Since the initial value (i.e the default) is an implementation detail of the blob module, it can be un-exported. Only the current MaxSquareSize param needs to be exported from the blob module.

[evan-forbes]

I'm fine with moving these, but I also definitely see the reasoning behind keeping them in the blob module since that's where we're planning on keeping these params