Allow aggregation of Artifact Upgrader data per artifact

[frzyc]

Currently, the artifact upgrader works per character loadout. For every new artifact, users tends to have to check several loadout builds to see if it would be an feasible upgrade. What if this process can work in reverse? For any artifact, users can check if its a viable upgrade for any of their existing builds?

At the very minimum, I would imagine a UI where, per artifact, we can have a list of upopt graphs, like in the artifact upgrader, but across all loadout/builds.

There are a few concerns:
Technical

• Would need to create a whole calculation for a character/loadout/build for every build on the account. this can be a lot, since it has to calculate both the base build and the upOpt Build. This will likely need to be heavily cached.
• would likely need to migrate the upOpt calc to a webworker, due to the above this calculation will be unlikely be fast.

Feasbility/Logic

• Even if an artifact may not be an immediate upgrade for all the builds, it may still be a possible "good" artifact if the builds use a different set/off piece.
• the comparable metric, of % chance x % increase, may not be universally comparable, since increase in one loadout target may be different in "perceived value" than another.