What is the technical name for a public key container in DER format?
As can be seen by RFC 5280 (X.509), this structure is the SubjectPublicKeyInfo. This field is formatted as follows:

SubjectPublicKeyInfo  ::=  SEQUENCE  {
     algorithm            AlgorithmIdentifier,
     subjectPublicKey     BIT STRING  }


The AlgorithmIdentifier is defined as follows:

AlgorithmIdentifier  ::=  SEQUENCE  {
     algorithm               OBJECT IDENTIFIER,
     parameters              ANY DEFINED BY algorithm OPTIONAL  }


The above two types define the format of the outer container in the ASN.1 in question (with the NULL value corresponding to the parameters field). The BIT STRING is an inner object defined by Appendix A.1.1 of PKCS #1 v2.1 as follows:

RSAPublicKey ::= SEQUENCE {
    modulus           INTEGER,  -- n
    publicExponent    INTEGER   -- e
}