Stop building aws-lc-sys, and axoupdater's image stack if a flag allows #203

Parent

#174

What to build

Stop compiling the two heaviest dependency stacks in a cold build. Configure reqwest/rustls to use the ring crypto provider instead of aws-lc, so that aws-lc-sys isn't built at all (its build script took 372s of a 616s cold build). Check whether axoupdater/axoasset has a feature flag that drops the image/moxcms/pxfm stack. If one exists, turn it off. If not, leave axoupdater alone and note the stack as a follow-up on #174: an upstream change or a replacement updater, not in scope here.

Acceptance criteria

• cargo tree -i aws-lc-sys (and aws-lc-rs) finds nothing
• HTTPS requests still verify certificates as before. The existing email and update tests pass, and a manual thirdshift update check against the real release endpoint still works
• The image stack is gone through a feature flag, or Make the test suite faster #174 has a comment explaining why it stays and what would remove it
• The PR reports the cold cargo test --no-run wall time against the Make the test suite faster #174 baseline
• The full suite passes

Blocked by

• Record the test suite baseline and make debug builds cheaper #202