personalization: fix SdKey.apply_val() implementation

'securityDomain' elements are decoded to ProfileElementSD instances,
which keep higher level representations of the key data apart from the
decoded[] lists.

So far, apply_val() was dropping binary values in decoded[], which does
not work, because ProfileElementSD._pre_encode() overwrites
self.decoded[] from the higher level representation.

Implement using
- ProfileElementSD.find_key() and SecurityDomainKeyComponent to modify
  an exsiting entry, or
- ProfileElementSD.add_key() to create a new entry.

Before this patch, SdKey parameters seemed to patch PES successfully,
but their modifications did not end up in the encoded DER.

(BTW, this does not fix any other errors that may still be present in
the various SdKey subclasses, patches coming up.)

Related: SYS#6768
Change-Id: I07dfc378705eba1318e9e8652796cbde106c6a52

pySim/esim/saip/__init__.py

@@ -1071,6 +1071,13 @@ class SecurityDomainKey:
                 'keyVersionNumber': bytes([self.key_version_number]),
                 'keyComponents': [k.to_saip_dict() for k in self.key_components]}
 
+    def get_key_component(self, key_type):
+        for kc in self.key_components:
+            if kc.key_type == key_type:
+                return kc.key_data
+        return None
+
+
 class ProfileElementSD(ProfileElement):
     """Class representing a securityDomain ProfileElement."""
     type = 'securityDomain'