workflows/(build-package.yaml -> standard-tests.yaml)

This commit reorganizes build-package.yaml in several ways:
- Follow name change of the called workflow
    The reusable workflow used by build-package.yaml changed name and
    location, and this commit follows the move.  It was located at
    ci/action-build-package before and has moved to ci/workflows,
    because what it provides is semantically more of a workflow than
    an action.
- Limit CI runs
    The commit also adds safeguards against too many CI runs. It
    limits them to PR events opened, re-opened or pushed-to, and to
    push events hitting branches master, main and release.
- Rename workflow itself to standard-tests.yaml
    That name reflects better what it represents: The entry point to
    janware's standard set of CI tests. All of them happen to run in
    the context of building and packaging at this point, but that
    might not be the only standard test this repo chooses to
    subscribe to in the future, and if so, they will be better off in
    one file with defined order, so give that file a better umbrella
    name.
Signed-off-by: Jan Lindemann <jan@janware.com>

.github/workflows/build-package.yaml

@@ -1,6 +0,0 @@
-name: Test repo on all supported platforms
-
-on: [pull_request, push]
-jobs:
-  CI:
-    uses: ci/action-build-package/.github/workflows/reusable.yaml@master

.github/workflows/standard-tests.yaml

@@ -0,0 +1,13 @@
+name: Standard CI tests
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+  push:
+    branches:
+      - master
+      - main
+      - released
+jobs:
+  CI:
+    name: Packaging test - All supported platforms
+    uses: ci/workflows/.github/workflows/test-packaging.yaml@master