gnrc_netif: move msg_queue to gnrc_netif struct

[benpicco]

Contribution description

Move the netif thread message queue to the gnrc_netif struct so we don't have to allocate it on the stack (and enlarge the stack when we use a larger queue).

Testing procedure

Most drivers will now have more free stack space, cc110x and nrf24l01p_ng should stay roughly the same as they would handle this manually previously.

Issues/PRs references

alternative to #17905

[benpicco]

I think I'd rather shrink the netif thread stack sizes than blacklisting more boards because the memory for the queue now moved from the stack to a static allocation.

[miri64]

I think I'd rather shrink the netif thread stack sizes than blacklisting more boards because the memory for the queue now moved from the stack to a static allocation.

Then please go ahead.

[maribu]

Code change looks good to me, but Murdock is not yet happy

[benpicco]

#17905 now does the same, but with a handy define for the default netif stack size