Add workflow to release on Maven Central

This commit adds a standard GHA workflow to perform a release, including
syncing with Maven Central using s01.oss.sonatype.org.

The release workflow kicks off based on tag that matches `vX.Y.Z` and
perform the following:

* Build the project
* Stage the bits to repo.spring.io
* Move the staging bits to Maven Central
* Promote the bits to repo.spring.io/release
* Generate a changelog using the issues matching the version

Closes gh-1812

.github/actions/await-http-resource/action.yml

@@ -0,0 +1,20 @@
+name: Await HTTP Resource
+description: 'Waits for an HTTP resource to be available (a HEAD request succeeds)'
+inputs:
+  url:
+    description: 'URL of the resource to await'
+    required: true
+runs:
+  using: composite
+  steps:
+    - name: Await HTTP resource
+      shell: bash
+      run: |
+        url=${{ inputs.url }}
+        echo "Waiting for $url"
+        until curl --fail --head --silent ${{ inputs.url }} > /dev/null
+        do
+          echo "."
+          sleep 60
+        done
+        echo "$url is available"

.github/actions/create-github-release/action.yml

@@ -0,0 +1,27 @@
+name: Create GitHub Release
+description: 'Create the release on GitHub with a changelog'
+inputs:
+  milestone:
+    description: 'Name of the GitHub milestone for which a release will be created'
+    required: true
+  pre-release:
+    description: 'Whether the release is a pre-release (a milestone or release candidate)'
+    required: false
+    default: 'false'
+  token:
+    description: 'Token to use for authentication with GitHub'
+    required: true
+runs:
+  using: composite
+  steps:
+    - name: Generate Changelog
+      uses: spring-io/github-changelog-generator@185319ad7eaa75b0e8e72e4b6db19c8b2cb8c4c1 #v0.0.11
+      with:
+        config-file: .github/actions/create-github-release/changelog-generator.yml
+        milestone: ${{ inputs.milestone }}
+        token: ${{ inputs.token }}
+    - name: Create GitHub Release
+      shell: bash
+      env:
+        GITHUB_TOKEN: ${{ inputs.token }}
+      run: gh release create ${{ format('v{0}', inputs.milestone) }} --notes-file changelog.md ${{ inputs.pre-release == 'true' && '--prerelease' || '' }}

.github/actions/create-github-release/changelog-generator.yml

@@ -0,0 +1,23 @@
+changelog:
+  repository: spring-projects/spring-webflow
+  sections:
+    - title: ":star: New Features"
+      labels:
+        - "type: enhancement"
+    - title: ":lady_beetle: Bug Fixes"
+      labels:
+        - "type: bug"
+        - "type: regression"
+    - title: ":notebook_with_decorative_cover: Documentation"
+      labels:
+        - "type: documentation"
+    - title: ":hammer: Dependency Upgrades"
+      sort: "title"
+      labels:
+        - "type: dependency-upgrade"
+  contributors:
+    exclude:
+      names:
+        - "bclozel"
+        - "rstoyanchev"
+        - "snicoll"

.github/actions/sync-to-maven-central/action.yml

@@ -0,0 +1,43 @@
+name: Sync to Maven Central
+description: 'Syncs a release to Maven Central and waits for it to be available for use'
+inputs:
+  jfrog-cli-config-token:
+    description: 'Config token for the JFrog CLI'
+    required: true
+  ossrh-s01-staging-profile:
+    description: 'Staging profile to use when syncing to Central'
+    required: true
+  ossrh-s01-token-password:
+    description: 'Password for authentication with s01.oss.sonatype.org'
+    required: true
+  ossrh-s01-token-username:
+    description: 'Username for authentication with s01.oss.sonatype.org'
+    required: true
+  spring-webflow-version:
+    description: 'Version of Spring Webflow that is being synced to Central'
+    required: true
+runs:
+  using: composite
+  steps:
+    - name: Set Up JFrog CLI
+      uses: jfrog/setup-jfrog-cli@9fe0f98bd45b19e6e931d457f4e98f8f84461fb5 # v4.4.1
+      env:
+        JF_ENV_SPRING: ${{ inputs.jfrog-cli-config-token }}
+    - name: Download Release Artifacts
+      shell: bash
+      run: jf rt download --spec ${{ format('{0}/artifacts.spec', github.action_path) }} --spec-vars 'buildName=${{ format('spring-webflow-{0}', inputs.spring-webflow-version) }};buildNumber=${{ github.run_number }}'
+    - name: Sync
+      uses: spring-io/nexus-sync-action@42477a2230a2f694f9eaa4643fa9e76b99b7ab84 # v0.0.1
+      with:
+        close: true
+        create: true
+        generate-checksums: true
+        password: ${{ inputs.ossrh-s01-token-password }}
+        release: true
+        staging-profile-name: ${{ inputs.ossrh-s01-staging-profile }}
+        upload: true
+        username: ${{ inputs.ossrh-s01-token-username }}
+    - name: Await
+      uses: ./.github/actions/await-http-resource
+      with:
+        url: ${{ format('https://repo.maven.apache.org/maven2/org/springframework/webflow/spring-webflow/{0}/spring-webflow-{0}.jar', inputs.spring-webflow-version) }}

.github/actions/sync-to-maven-central/artifacts.spec

@@ -0,0 +1,20 @@
+{
+  "files": [
+    {
+      "aql": {
+        "items.find": {
+          "$and": [
+            {
+              "@build.name": "${buildName}",
+              "@build.number": "${buildNumber}",
+              "path": {
+                "$nmatch": "org/springframework/webflow/webflow/webflow-*.zip"
+              }
+            }
+          ]
+        }
+      },
+      "target": "nexus/"
+    }
+  ]
+}