Clarify the usage of encodings which can result in non-determinism

[highlunder]

Examples include general byte encodings of extensions, or the handling of otherName in General Name (Types)

[highlunder]

This is related to the bigger determinism-issue discussed in #197

[gselander]

Check if the same strategy as in #197 applies to otherName

[gselander]

otherName in general is encoded [ ~oid, bytes ]. The three negative values in the Section 9.9 C509 General Names Registry register encodings for otherName with BundleEID / SmtpUTF8Mailbox / hardwareModuleName.

This opens for different encodings, so for deterministic encoding it is required to introduce some restrictions, for example only use the dedicated encodings.