This will make it easier to support both string types at the same time
while we convert code, and tracking down remaining uses.
One big exception is Value::to_string() in LibJS, where the name is
dictated by the ToString AO.
Subject alternative name entries containing IP addresses will now be
parsed and added to the list of SANs. This should allow for certificate
verification when accessing IP addresses directly.
Root and intermediate CA certificates should have these extensions set
to indicate that they are allowed to sign other certificates. The values
reported in these extensions is now also checked by `verify_chain` to
make sure no non-CA certificates are used to sign another certificate.
The certificate parser now also aborts when a critical extension is
detected which is unsupported, as is required by the specification.
The ASN.1 decoder was originally using AK::BitmapView for decoded
BitStrings, however the specification requires that the bits are stored
in a byte from the most significant to the least significant.
Storing three bits '110' would result in a byte '1100 0000', i.e. 0xC0.
However, AK::BitmapView expects the bits to be stored at the bottom like
'0000 0110', i.e. 0x06. For the current uses the data was always a
multiple of eight bits, resulting in complete bytes, which could
directly be interpreted correctly.
For the implementation of the key usage extension of certificates the
correct implementation of the BitString is required.
With this change the certificate chain sent by the server will actually
be verified, instead of just checking the names of the certificates.
To determine if a certificate is signed by a root certificate, the list
of root certificates is now a HashMap mapping from the unique identifier
string to the certificate. This allows us to take the issuer of a
certificate and easily check if it is a root certificate. If a
certificate is not signed by a root certificate, we will check that it
is signed by the next certificate in the chain.
This also removes the ad-hoc checking of certificate validity from
multiple places, and moves all checking to the verify_chain.
