action.yml / reusable.yaml: Remove and rename

This repository has changed its name and location from "workflow-build-packages" to "workflows".
It has not been renamed to "workflow-build-packages", because it might contain other workflows in the future, likely reusable workflows.
The reason behind the name change is that the repo has changed its purpose. The composite action it has primarily provided, with its distribution matrix and all, has done more than the tiny thing an action should provide all along, so this was a bad fit, and the toplevel "action.yml" is removed by this commit. "reusable.yaml" in .github/workflows is renamed to "test-packaging.yaml", because it would otherwise collide with other possible future workflows in this repo.
Signed-off-by: Jan Lindemann <jan@janware.com>

action.yml

@@ -1,34 +0,0 @@
-name: jw-pkg packaging test
-description: Checkout, build and test a project organized with jw-pkg
-
-runs:
-  using: composite
-  steps:
-    - uses: ci/action-checkout@main-jw
-      with:
-        path: ${{ github.event.repository.name }}
-        working-directory: ${{ github.event.repository.name }}
-        persist-credentials: false
-    - name: Install build prerequisites
-      shell: bash
-      run: |
-        set -euxo pipefail
-        # Install from source what's publicly available. This step could be omitted.
-        (
-          export PROJECTS_DIR_REMOTE_BASE=${{ github.server_url }}
-          owner=janware
-          makefile=$PROJECTS_DIR_REMOTE_BASE/$owner/jw-pkg/raw/branch/master/make/projects-dir-minimal.mk
-          curl --create-dirs -o build-jw-foss/Makefile $makefile
-          make -C build-jw-foss pkg-manager-refresh
-          make -C build-jw-foss pkg-install-release-deps
-          OFFLINE=true make -C build-jw-foss pkg-rebuild-reinstall
-        )
-
-    - name: Build and install package
-      shell: bash
-      run: |
-        set -ex
-        make -C ${{ github.event.repository.name }} pkg-manager-refresh # redundant
-        make -C ${{ github.event.repository.name }} pkg-install-testbuild-deps # redundant
-        make -C ${{ github.event.repository.name }} pkg-rebuild
-        make -C ${{ github.event.repository.name }} pkg-reinstall