fix: kanata definition of the fn layer does not follow documentation

[Erwyn]

There are differences between what the documentation of the function layer describes and what the Kanata layout really does about it. This commit should fix:

1. The function layer is now locked
2. Pressing lalt or ralt result to a switch to base
3. lalt and lctl were swapped to match the order of the homerow

I realize 1&2 might have been on purpose in which case the issue is the documentation. I just wanted to provide with a quick fix if it was not the case.

In any event I feel like swapping lalt and lctl is a good thing as it should match the order of the homerows in my opinion.

I would be more than happy to discuss all of this.