Refactor rend_cache_lookup_entry() and how it's used

Here is why:

1) v0 descriptors are deprecated since 0.2.2.1 and not suppose to be alive
in the network anymore. This function should only serve v2 version for now
as the default.

2) It should return different error code depending on what's the actual
error is. Right now, there is no distinction between a cache entry not found
and an invalid query.

3) This function should NOT test if the intro points are usable or not. This
adds some load on a function that should be "O(1)" and do one job.
Furthermore, multiple callsites actually already test that doing twice the
job...

4) While adding control event, it would be useful to be able to lookup a
cache entry without having it checking the intro points. There are also
places in the code that do want to lookup the cache entry without doing
that.

Fixes #14391

Signed-off-by: David Goulet <dgoulet@ev0ke.net>

0 files changed, 0 insertions, 0 deletions