flux: update flux-core package and add a flux-sched package (#8818)

Renames the flux package to flux-core and updates its dependencies, versions,
and variants. Adds a flux-sched package.

This also updates two flux-core dependencies: lua and czmq.

var/spack/repos/builtin/packages/czmq/package.py

@@ -30,6 +30,7 @@ class Czmq(AutotoolsPackage):
     homepage = "http://czmq.zeromq.org"
     url      = "https://github.com/zeromq/czmq/archive/v4.0.2.tar.gz"
 
+    version('4.1.1', 'a2ab03cddd14399c6ba75b030a256211')
     version('4.0.2', 'a65317a3fb8238cf70e3e992e381f9cc')
     version('3.0.2', '23e9885f7ee3ce88d99d0425f52e9be1')
 
@@ -37,6 +38,7 @@ class Czmq(AutotoolsPackage):
     depends_on('automake', type='build')
     depends_on('autoconf', type='build')
     depends_on('pkgconfig', type='build')
+    depends_on("libuuid")
     depends_on('zeromq')
 
     def configure_args(self):