workflows: Add a manually trigger "devel" workflow for the CI

This workflow is intended to replace the `workflow_dispatch` trigger
currently present as part of the `ci-nightly.yaml`.

The reasoning behind having this done in this way is because of our good
and old GHA behaviour for `pull_request_target`, which requires a PR to
be merged in order to check the changes in the workflow itself, which
leads to:
* when a change in a workflow is done, developers (should) do:
  * push their branch to the kata-containers repo
  * manually trigger the "nightly" CI in order to ensure the changes
    don't break anything
    * this can result in the "nightly" CI weather being polluted
      * we don't have the guarantee / assurance about the last n nightly
	runs anymore

Signed-off-by: Fabiano Fidêncio <fabiano@fidencio.org>

.github/workflows/ci-devel.yaml

@@ -0,0 +1,17 @@
+name: Kata Containers CI (manually triggered)
+on:
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  kata-containers-ci-on-push:
+    uses: ./.github/workflows/ci.yaml
+    with:
+      commit-hash: ${{ github.sha }}
+      pr-number: "manually-triggered"
+      tag: ${{ github.sha }}-manually-triggered
+      target-branch: ${{ github.ref_name }}
+    secrets: inherit