Remove remaining v0 hidden service descriptor code.

Fixes the rest of #10841 after #10881 already removed some hidden service
authority code.
Remove another unused v0 hidserv function.

Noted by Nick on #10841.
tristate->enum in rendcommon functions

When we have more than two return values, we should really be using
an enum rather than "-2 means this, -1 means that, 0 means this, and
1 or more means a number."
Merge remote-tracking branch 'public/bug10841'