net/netip: use slice-to-array conversions
net/netip: use slice-to-array conversions

Use slice-to-array conversions in AddrFromSlice and
(*Addr).UnmarshalBinary. This allows allows to use AddrFrom16 and drop
the redundant ipv6Slice helper.

For #46505

Change-Id: I0e3a7d8825ad438115b7f23ee97cc74eec41a826
Reviewed-on: https://go-review.googlesource.com/c/go/+/432735
Reviewed-by: Damien Neil <7e091e9a80da888fcd7836fd3c6b7b85f4677c12@google.com>
Run-TryBot: Tobias Klauser <0a68dd4915066ec5d3f81f75a828fee53dcc8822@gmail.com>
Auto-Submit: Tobias Klauser <0a68dd4915066ec5d3f81f75a828fee53dcc8822@gmail.com>
Reviewed-by: Cherry Mui <d62e63aa42ce272d7b6a5055d97e942b33a34679@google.com>
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

golang/go,golang/go,golang/go,golang/go,golang/go,golang/go,golang/go,golang/go