Create/consolidate issues about 3.1 usability

[mpg]

Several issues have been reported regarding usability issues introduced in 3.0 (most of them related to making fields private), some of which have not been resolved in 3.1, see for example #5331. Oftentimes several problems are reported at once, which makes sense from the reporter's perspective, but is not ideal for us to act on.

This task is to create a consolidated list of actionable issues (either can be resolved directly, or clearly identify as a study task) covering all usability issues in 3.1 that have been reported on github or on the mailing list.

[mpg]

See also:

• mbedtls_ssl_context private fields getters #5184 (SSL, CID)
• Add public getters/setters for mbedtls_md5_context, mbedtls_sha1_context etc #5198 (MD/SHA, to be confirmed, probably not needed)
• mbedtls_timing_delay_context private fields getters #5183 (discuss to confirm need?)
• Members of mbedtls_ecp_keypair should be public or have accessors #4838 (ECP keypair)
• Missing getters on some fields #5005 (PK, ECP keypair)

[mpg]

I think this is done. All the points in #5331 that needed action have been split to a specific issues, and those have been added to the "High-priority 3.0 follow-up" EPIC when relevant.

Searches have been done to identify all existing issues relevant to that EPIC. When there was overlap, it has been noted with links to related issues, and issues that were fully redundant have been closed as duplicates.

Also, all issues in the EPIC are now estimated.