perf: add basic precompilation

[mortenpi]

This gets "TTFA" (time-to-first-authentication) down from 5s to 2.4s, and TTFD (time-to-first-dataset-listing) from ~8s to 4.5-5 (and similar for time-to-first-job-submission). Precompilation time went from 3-4s -> 10-12s.

The test scripts was the following:

# TTFA
using JuliaHub
auth = JuliaHub.authenticate("...")
display(auth)
# + this for TTFD
datasets = JuliaHub.datasets()
display(datasets)

So about 50% improvement. It would be nice if it was better, but still something. As a side note: I don't see too many interesting things in --trace-compile, so I wonder if the rest of the compilation time are invalidations or something like that..

[zot]

So about 50% improvement. It would be nice if it was better, but still something. As a side note: I don't see too many interesting things in --trace-compile, so I wonder if the rest of the compilation time are invalidations or something like that..

Don't sell yourself short -- it's twice as fast! That is a 100% improvement!

Can't think of another meaning for 100% improvement off the top of my head...