Fuzzfetch

- allow missing symbols for fuzzing builds (all have crashreporter
disabled now, only historical builds should have them).

- add `-V`/`--version` to command-line
- don't resolve ESR version if `--build` is a namespace
- add autoland to branch search regex
- fix naming for autoland branches

- Remove support for inbound
- Download geckoview_example for `--os Android`
- Use SI units for data rates, and IEC units for file sizes
- Export fetching utility functions `download_url` and `get_url`.

Print where the build was extracted to.

Fix opt to use shippable builds from taskcluster.