Add missing testplans from other components

kernel-ark-build to build latest upstream kernel-ark sources with clang
lld-alternative to test update-alternatives upon install/uninstall

tests/kernel-ark-build.fmf

@@ -0,0 +1,23 @@
+summary: Build latest kernel-ark with clang using different build configurations
+discover:
+    how: fmf
+    url: https://src.fedoraproject.org/tests/clang.git
+    ref: main
+    test: kernel-ark-build
+execute:
+    how: tmt
+provision:
+    hardware:
+        memory: ">=16 GiB"
+        cpu:
+            cores: ">=8"
+adjust:
+  - because: "Plan to be ran when either executed locally, or executed by CI system to gate a build or PR."
+    when: >-
+      trigger is defined
+      and trigger != commit
+      and trigger != build
+    enabled: false
+  - because: "Rebuilding kernel-ark is relevant only to rawhide"
+    when: distro is not defined or distro != fedora-rawhide
+    enabled: false

tests/lld-alternatives.fmf

@@ -0,0 +1,20 @@
+summary: LLD tests for build/PR gating, testing alternatives and spoiling the installation
+adjust:
+  - because: "Plan to be ran when either executed locally, or executed by CI system to gate a build or PR."
+    when: >-
+      trigger is defined
+      and trigger != commit
+      and trigger != build
+    enabled: false
+
+discover:
+    - name: lld-tests
+      how: fmf
+      url: https://src.fedoraproject.org/tests/lld.git
+      ref: main
+      test: ld-alternative
+execute:
+    how: tmt
+provision:
+  hardware:
+    memory: ">= 4 GiB"