Unfortunately, G::from_bytes doesn't require canonicity so that still can't
be properly tested for. While we could try to detect SEC1, and write tests
on that, there's not a suitably stable/wide enough solution to be worth it.
The audit recommends checking failure cases for from_bytes,
from_bytes_unechecked, and from_repr. This isn't feasible.
from_bytes is allowed to have non-canonical values. [0xff; 32] may accordingly
be a valid point for non-SEC1-encoded curves.
from_bytes_unchecked doesn't have a defined failure mode, and by name,
unchecked, shouldn't necessarily fail. The audit acknowledges the tests should
test for whatever result is 'appropriate', yet any result which isn't a failure
on a valid element is appropriate.
from_repr must be canonical, yet for a binary field of 2^n where n % 8 == 0, a
[0xff; n / 8] repr would be valid.
