[context] support "disable_excludes" config option
[context] support "disable_excludes" config option

The "disable_excludes" contains a list of repository ids.
A user defined excludes and includes are ignored for repositories
in the list.
Special meaning:
"all" - ignore all user defined excludes and includes
"main" - ignore user defined excludes and includes from global config

rpm-software-management/libdnf,hughsie/libhif,rpm-software-management/libdnf,hughsie/libhif,hughsie/libhif,rpm-software-management/libdnf,rpm-software-management/libhif,rpm-software-management/libdnf,rpm-software-management/libhif,rpm-software-management/libhif,hughsie/libhif,rpm-software-management/libhif