teams/kde: Rework to add disk image build

This adds a disk image build profile to produce Fedora KDE images.
Additionally, these profiles are now tested in CI.

tmt/plans/desktop/kde/build-desktop-disk.fmf

@@ -0,0 +1,8 @@
+summary: Build KDE Desktop disk image
+discover:
+    how: fmf
+environment:
+    image_type: oem
+    image_profile: KDE-Desktop-Disk
+execute:
+    how: tmt

tmt/plans/desktop/kde/build-desktop-live.fmf

@@ -0,0 +1,8 @@
+summary: Build KDE Desktop live image
+discover:
+    how: fmf
+environment:
+    image_type: iso
+    image_profile: KDE-Desktop-Live
+execute:
+    how: tmt