Argument typestring graph path second pass

Quality graph path pass: Second pass that ensures quality arguments are maintained throughout as necessary.

Currently, for example, STL-> PNG just makes a 500x500 PNG. But what if we want 1024x1024 thumb?

So, after a path is determined, we go through again and attach all necessary arguments. Arguments have to be carried through in order to ensure the right hashes for each Resource.

This might require an addition to the type system, or at least improvements or added structure to the cache system (e.g. dimensions is always first argument)

Start by tracing how the conversion graph determines a path and how arguments are represented for each Resource. Review the type system and cache structure, especially how dimensions and hashes are handled. Done means a second pass carries all necessary quality arguments, such as 1024x1024 dimensions from STL to PNG, and produces distinct resource hashes.

Written by the indexing model from the issue text.