Remove ext/mbedtls-asn1

[d3zd3z]

This directory was intended to be a snapshot of the ASN.1 code from Mbed TLS. With newer versions, this gets fairly large, as there are lots of include files that get brought in. Instead of this, just rely on the mbed TLS library being provided externally when ASN.1 parsing is needed.

[de-nordic]

Do we even need the ASN.1 ? As far as I understand it is used because we compile the key in such form, but why not just compile the raw key, without the encoding? Saves us code, saves us data, saves us run-time decoding.

[github-actions[bot]]

This issue has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this issue will automatically be closed in 14 days. Note, that you can always re-open a closed issue at any time.