Add treeinfo for "secondary" architectures & "catch-all" fallbacks for Fedora, RHEL, and CentOS 7.
This MR aims to add support for:
- RHELSA treeinfo;
- RHEL-ALT treeinfo;
- CentOS7 "secondary" architectures treeinfo;
- Fedora[11-28] "catch-all" treeinfo;
- Fedora 29, 30, and Rawhide "secondary" architectures treeinfo;