fix: execute statement reliable

[juleswritescode]

I've been through many iterations but this seems to be the simplest.

We use a dedicated connection for the prepare statement and close it on drop. This will clear all the prepared statements for that session. sqlx itself doesn't cache anything when using prepare. If we worry about performance overhead, I suggest we a) use sqlx cache via prepare_with and b) debounce the publishing of diagnostics again 👍

[psteinroe]

after the ordering was removed this makes me very happy! there is one unused import but other than that great job!