SIMBAD cache question

@ManonMarchand in #2954, the caching machinery was removed in favor of `lru_cache`. My understanding is that this cache does not persist between sessions, it's purely in-memory, which is quite different from the previous mode.

Did you give any thought to a means for session-to-session caching as we had previously? This was my main use case. I discovered today that I'm unintentionally spamming SIMBAD with massive numbers of repeat requests because I thought I was using cached queries but was not.

@bsipocz do you have any feedback on this? The caching system was the source of some user problems in the past, but it was _incredibly_ useful.

Start by reviewing issue #2954 and the current SIMBAD caching approach using Python's lru_cache. Determine how session-to-session caching previously worked and what persistence behavior is required. Done means repeat SIMBAD requests can reuse cached results across sessions without unintentionally issuing large numbers of duplicate requests.

Written by the indexing model from the issue text.