Test cases for asn1c APER encoding
asn1c has a quite good testsuite for all the encoders/decoders present in upstream.
The APER support patch we imported from eurecom unfortunately comes without any testsuite and hence is based on "belief" rather than "verifyable trust". Let's create a test suite to see where we stand.
This can help us with porting/rebasing (see #2435)