[improvement]: check public/private cert/key details

[oza4h07]

Improvement Description

Stir-Shaken relies on public and and private certs.
These certs are not independent from each other.
Checking a public cert is complaint with a private one, cannot be done by simply looking at the cert name or at the cert content.
Due to this, even a seasoned sysadmin can easily mix certs and configure Asterisk's stir Shaken module, to use a public cert which is incompatible with a private one

A welcome improvement would be to automatically check cert compliance when configuration is re-loaded and notify sysadmin when a mismatch or error is detected.