Set the "virtual_streams" for platform modules in MBS.

By grouping the platform modules together using the "virtual_streams",
we can allow a module built against platform:f30 to buildrequire module
built against platform:f29 (if that module "requires: platform: []").

This fixes https://pagure.io/fm-orchestrator/issue/1243.

More info:

- https://pagure.io/fm-orchestrator/pull-request/1281
- https://pagure.io/fm-orchestrator/blob/master/f/docs/DEPENDENCY_RESOLUTION.rst
- https://pagure.io/fm-orchestrator/blob/master/f/docs/VIRTUAL_MODULES.rst

roles/mbs/common/files/default-modules.production/platform-f29.yaml

@@ -22,6 +22,7 @@ data:
       requires: {}
       koji_tag: module-f29-build
       mse: TRUE
+      virtual_streams: [fedora]
 document: modulemd
 version: 1
 

roles/mbs/common/files/default-modules.production/platform-f30.yaml

@@ -22,6 +22,7 @@ data:
       requires: {}
       koji_tag: module-f30-build
       mse: TRUE
+      virtual_streams: [fedora]
 document: modulemd
 version: 1
 

roles/mbs/common/files/default-modules.production/platform-f31.yaml

@@ -22,6 +22,7 @@ data:
       requires: {}
       koji_tag: module-f31-build
       mse: TRUE
+      virtual_streams: [fedora]
 document: modulemd
 version: 1
 

roles/mbs/common/files/default-modules.production/platform-f32.yaml

@@ -22,6 +22,7 @@ data:
       requires: {}
       koji_tag: module-f32-build
       mse: TRUE
+      virtual_streams: [fedora]
 document: modulemd
 version: 1
 

roles/mbs/common/files/default-modules.staging/platform-f29.yaml

@@ -22,6 +22,7 @@ data:
       requires: {}
       koji_tag: module-f29-build
       mse: TRUE
+      virtual_streams: [fedora]
 document: modulemd
 version: 1
 

roles/mbs/common/files/default-modules.staging/platform-f30.yaml

@@ -22,6 +22,7 @@ data:
       requires: {}
       koji_tag: module-f30-build
       mse: TRUE
+      virtual_streams: [fedora]
 document: modulemd
 version: 1
 

roles/mbs/common/templates/config.py

@@ -207,3 +207,12 @@ class ProdConfiguration(BaseConfiguration):
     KOJI_CG_DEVEL_MODULE = False
 
     MODULES_ALLOW_SCRATCH = True
+
+    # By default, MBS allows buildrequiring only modules built against
+    # compatible version of platform base module. By compatible, we mean
+    # less or equal minor number of "stream_version". For example, when building module
+    # against platform:f30, it wouldn't be possible to buildrequire a module
+    # built against platform:f29. This is not intended behaviour in Fedora
+    # and therefore we want to turn this feature off.
+    ALLOW_ONLY_COMPATIBLE_BASE_MODULE = False
+