Remove access to the keybase object from all REST endpoints

[zmanian]

Every REST tx endpoint that currently takes a keybase object is potential a misuse vector by someone who misuses the RESTS service as a hosted key management system.

This was only intended for use in local applications. Voyager will no longer operate in this mode.

As practical matter it would be doable to just remove access to the keybase object.

I think the bigger thing is going to be ensuring that there are equivalent generate, sign, broadcast tests for all the code paths where we remove just using server side signing.

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged
• Contributor assigned/self-assigned

[alexanderbez]

We already achieve this somewhat via: #3640

Alternatively, I made an issue which is essentially a dup of this issue I believe: #3641

[alessio]

As @alexanderbez suggests, this is easily achievable by working #3641 out. All requests would then operate in generate mode only. We should strip out the code handling certificates for the REST server altogether too.

[alexanderbez]

This has been addressed.