Refactor planner factory rendering to only display singular factories at a time

[Maelstromeous]

In order to resolve a massive problem in the planner, performance, and rather than going down the route of adding rendering / "dom lazy rendering" and even "check if factory is dirty" validation hacks, there's a very simple solution:

Only render one factory at a time in the DOM.

This would mean a lot more use out of the sidebar navigation, and this would have to be improved on mobile as it's currently not great UX. But this would eliminate:

• The need for a "loader", as it'll just render the first factory which will be nearly instant.
• This removes the "computation delay" that we currently have when Vue attempts to update DOM elements.
• It MASSIVELY will reduce lag.
• The number of factories supported by planner can increase massively, as it simply won't care much about DOM rendering. Calculations will hit a theoritical limit though.
• We can remove the "hiding" factories nag / jack, as there is nothing left to really need to hide.
• Mobile phones / low spec PCs won't scream begging for a bullet between the brain.
• Browsers won't crash.

While it may not be as "flashy" as being able to scroll down, what we can do is implement when they hit the "bottom" of a factory view if they continuing scrolling it'll push them to the next factory.

Or, we add a big nice button at the bottom of the factory kind of like a "next" button, e.g.:

[ Link to previous factory ]
[ Maybe we link to import factories? ]
-----
This is my factory

These are my products

Blah blah blah

------
[ Link to next factory ]
[ Maybe we link to export factories? ]