validateEmail incorrectly tests results of std.net.isemail.isEmail()

[radcapricorn]

vibe.utils.validation.validateEmail tests the results of std.net.isemail.isEmail like this:

return isEmail(str) != EmailStatusCode.valid;

However, isEmail returns EmailStatus, not EmailStatusCode. Incidentally, EmailStatus aliases self to a bool property valid(), which allows the code above to compile. But the logic is reversed, since EmailStatusCode.valid == 0, although isEmail(str) == false when the e-mail is invalid.
Paired with Phobos fixes between versions, this leads to further inconsistencies at run time.
For example, with dmd 2.071.1 (when there was an issue in Phobos):

auto result = isEmail("[email protected]");
/*
result == EmailStatus
{
    valid: false
    localPart: a
    domainPart: b.c
    statusCode: error
}
*/
auto err = appender!string();
auto vibeResult = validateEmail(err, "[email protected]");
/*
vibeResult == true
*/

Even though isEmail() (incorrectly) returned an invalid status, vibe treats it as valid.
And with current dmd nightly:

auto result = isEmail("[email protected]");
/*
result == EmailStatus
{
    valid: true
    localPart: a
    domainPart: b.c
    statusCode: valid
}
*/
auto err = appender!string();
auto vibeResult = validateEmail(err, "[email protected]");
/*
vibeResult == false
err.data == "The email address is invalid."
*/

Vice-versa, isEmail() now correctly returns a valid status, but vibe treats it as invalid.

[radcapricorn]

Note: Phobos issue mentioned above holds for Phobos included with dmd 2.071.2 as well. The proposed fix would effectively break validateEmail() for anyone not using nightly dmd/Phobos builds.

[s-ludwig]

Fixed by #1582.