fmf: Factorize and merge plan files

FMF plans can inherit common properties [1]. Go back to a single
plans/all.fmf (like it was until commit fe4721cdcd), put the common
properties at the top, and enumerate the three plans with their specific
properties.

This will make it easier to keep the Fedora downstream dist-git in sync.

[1] https://tmt.readthedocs.io/en/latest/examples.html#inherit-plans

plans/all.fmf

@@ -0,0 +1,19 @@
+discover:
+    how: fmf
+execute:
+    how: tmt
+
+/basic:
+    summary: Run tests for basic packages
+    discover+:
+        test: /test/browser/basic
+
+/network:
+    summary: Run tests for cockpit-networkmanager
+    discover+:
+        test: /test/browser/network
+
+/optional:
+    summary: Run tests for optional packages
+    discover+:
+        test: /test/browser/optional

plans/basic.fmf

@@ -1,7 +0,0 @@
-summary:
-    Run tests for basic packages
-discover:
-    how: fmf
-    test: /test/browser/basic
-execute:
-    how: tmt

plans/network.fmf

@@ -1,7 +0,0 @@
-summary:
-    Run tests for cockpit-networkmanager
-discover:
-    how: fmf
-    test: /test/browser/network
-execute:
-    how: tmt

plans/optional.fmf

@@ -1,7 +0,0 @@
-summary:
-    Run tests for optional packages
-discover:
-    how: fmf
-    test: /test/browser/optional
-execute:
-    how: tmt