This will be used in `samba-tool user keytrust delete` and `samba-tool
computer keytrust delete` and is mainly to deduplicate that code.

Potentially it could also be used in `keytrust view`.

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>

This compares the key material and DN of a KeyCredentialLinkDn with a
list of others, which is a different sense of equality than the
default (which considers GUIDs and binary equality).

This will be used by samba-tool to check whether a link is in fact a
duplicate even if it seems not to be due to some insignificant field
being non-identical.

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>

'auto' is the same as None. This is helpful to samba-tool.

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>

In samba-tool we are going to want a KeyCredentialLinkDn to be able
to describe itself. We're adding the methods here because
`samba-tool user` and `samba-tool computer` will both want to use
them.

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>

int.to_bytes assumed these defaults in recent versions

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>

We want to ensure the as best we can that the binary blob is in a
useful format. This will be used by samba-tool.

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>

This works as a BinaryDn, but it also does validation to ensure the
binary contains a KEYCREDENTIALLINK_BLOB.

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>