Allow different type of error categories in the different error monads

We will want to add a new type of category of error for tenderbake Outdated.

Since this is exposed in the protocol environment, we need to functorize the error monad builder over the error category to allow producing a different one for every protocol.

By the way, those categories are unused for the shell errors. This will also allow to replace those categories by unit

Notice that this somewhat breaks find_info_of_error for wrapped error: since the category of the wrapped error is not necessarily representable in the nesting one, the category of the info is going to be wrong. So I simply chose to replace it by the default category in this case. This is only used for serialization, maybe we should add a category_name field of type string ?