configure: put the "advanced mode" in a new tab instead of a link

[brliron]

Suggestion from Lance. On the patch selection page, instead of having just the list of languages with a small and scary "advanced mode..." link, have two tabs: the default tab would be "Languages", with the current default UI, and the other tab could be "Other patches", "Gameplay patches", "All patches", or something else that tells right away that non-language patches exist, and that could invite a curious user to try some of them. Inside this tab, we would have the same advanced UI, just with a more enticing name.

The aim of this change is to improve discoverability of non-translation patches.
Because, with this change, switching between the two tabs feels more natural, the simple view (with only the languages) should reflect better any change that the advanced view would have done. For example, below the radio buttons, write the list of patches added from advanced mode, and have no radio button checked if the user removed the language from the advanced view.

If we want to try it, we need to implement it in a branch and to do some user testing before merging it:

• How does a casual user tasked with installing a translation patch react? Ideally, they should either ignore the new tab, or go to the new tab and quickly go back to the original one (if they go to the new tab and use the advanced mode successfully and without struggle, they're probably too advanced for this test).
• How does an user without any set goal act? Do they want to explore that part? Do they ignore it? Should probably be tested on several users of various skill level.
• We tell the test user "you can install the patch xxx by xxx using thcrap" (that's the kind of scenario that a Touhou fan seeing a patch creator advertising their patch on Twitter would encounter), and let them try to install it without any further help.

Scenario 3 can be done right after scenario 1 by the same user - they did something simple, we ask for a more advanced task, their prior knowledge won't help. Scenario 2 should be done by a different user / group of users, because both 1 and 2 need a user who never saw the new UI with tabs (or even someone who never used thcrap configure v3 at all).

The part about making sure the simple tab shows the changes in the advanced tab don't need to exist for the user testing, I'm mostly concerned on how they will react to the tabbed UI.

[lilyremigia]

See https://github.com/tudi20/thcrap/tree/page2-tabbed