rust: num: add `into_bool` method to `Bounded`

rust: num: add `into_bool` method to `Bounded`

Single-bit numbers are typically treated as booleans. There is an
`Into<bool>` implementation for those, but invoking it from contexts
that lack type expectations is not always convenient.

Add an `into_bool` method as a simpler shortcut.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Tested-by: Dirk Behme <dirk.behme@de.bosch.com>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://patch.msgid.link/20260314-register-v9-3-86805b2f7e9d@nvidia.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>