* `std.builtin.Panic` -> `std.builtin.panic`, because it is a namespace.
* `root.Panic` -> `root.panic` for the same reason. There are type
checks so that we still allow the legacy `pub fn panic` strategy in
the 0.14.0 release.
* `std.debug.SimplePanic` -> `std.debug.simple_panic`, same reason.
* `std.debug.NoPanic` -> `std.debug.no_panic`, same reason.
* `std.debug.FormattedPanic` is now a function `std.debug.FullPanic`
which takes as input a `panicFn` and returns a namespace with all the
panic functions. This handles the incredibly common case of just
wanting to override how the message is printed, whilst keeping nice
formatted panics.
* Remove `std.builtin.panic.messages`; now, every safety panic has its
own function. This reduces binary bloat, as calls to these functions
no longer need to prepare any arguments (aside from the error return
trace).
* Remove some legacy declarations, since a zig1.wasm update has
happened. Most of these were related to the panic handler, but a quick
grep for "zig1" brought up a couple more results too.
Also, add some missing type checks to Sema.
Resolves: #22584
formatted -> full
