(gh-29) Switch acceptance workflow to dispatch

Now that kvm_automation_tooling/action.yaml accepts
parameters for openvox_version and can test pre-release builds from the
artifacts.overlookinfratech.com server, switch to a workflow_dispatch.

Until such a time as there is a build step that would build and push
packages to an artifacts server, a pr or branch push event isn't
meaningful to test against aside from validating the gha acceptance.yaml
workflow itself, since we would just be validating an already released
package unreleated to the code in the pr or, for most cases outside of a
release tag, the branch.

Author: jpartlow

.github/workflows/acceptance.yaml

@@ -1,10 +1,36 @@
 name: Acceptance Tests
 
 on:
-  push:
-    branches: [main]
-  pull_request:
-    branches: [main]
+  workflow_dispatch:
+    inputs:
+      pre-release-build:
+        description: |-
+          (Pre-release Build) Whether to test unreleased version
+          packages from the artifacts server, or released packages
+          from the given collection.
+
+          If this is true, version must be a valid version, not
+          latest, and collection is ignored. The workflow will
+          download and install the matching openvox-agent package file
+          from the artifacts-url server.
+
+          If this is false, version and collection must match, and the
+          workflow will install the given openvox collection package
+          and then let the system package manager install the latest
+          or version package from the collection repository.
+        default: true
+        type: boolean
+      version:
+        description: '(Version) Package version to test. (required if Pre-release Build is true)'
+        type: string
+      collection:
+        description: '(Collection) OpenVox collection to use. (ignored if Pre-release Build is true)'
+        default: 'openvox8'
+        type: string
+      artifacts-url:
+        description: 'URL to the artifacts server. (used if Pre-release Build is true)'
+        default: 'https://s3.osuosl.org/openvox-artifacts'
+        type: string
 
 permissions:
   contents: read
@@ -21,6 +47,7 @@ jobs:
         os:
           - ubuntu
         os-version:
+          - '18.04'
           - '20.04'
           - '22.04'
           - '24.04'
@@ -36,6 +63,11 @@ jobs:
           os-arch: x86_64
           host-root-access: true
           ruby-version: ${{ env.RUBY_VERSION }}
+          install-openvox: true
+          openvox-version: ${{ github.event.inputs.version }}
+          openvox-collection: ${{ github.event.inputs.collection }}
+          openvox-released: ${{ ! github.event.inputs.pre-release-build }}
+          openvox-artifacts-url: ${{ github.event.inputs.artifacts-url }}
           vms: |-
             [
               {