Force `PRJ_BUILD` to `Release` to avoid `-gnatwe` and compilation issue:
```
templates_parser.adb:2093:55: warning: pragma Unreferenced given for "Next_Last" [enabled by default]
```
Also applied the rest of transformations described in alire#227: no top-level
[genera] table, name/version keys, [[depends-on]] array instead of table.
Crates without maintainer or pending migration remain in /orphaned
GitHub URLs rely on the default tarballs that at some point will
have to be released with uploaded binaries (with `alr publish` support).