Add publish workflow. (#7)

Partial #2

.github/env/Linux/gradle.properties

@@ -2,3 +2,13 @@
 # we shouldn't rely on gradle for any of this logic.
 org.gradle.java.installations.auto-download=false
 org.gradle.java.installations.auto-detect=false
+
+# https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners#supported-runners-and-hardware-resources
+# GitHub hosted linux runner environment has 2 CPUs and 7G RAM.
+#
+# Turning off parallelism makes things a bit more deterministic, and is specifically neded for publishing
+# (to ensure we don't create disjointed staging repositories).
+
+org.gradle.parallel=false
+org.gradle.workers.max=1
+org.gradle.jvmargs=-Xmx6g

.github/workflows/check.yml

@@ -4,7 +4,7 @@ on:
   pull_request:
     branches: [ main ]
   push:
-    branches: [ main ]
+    branches: [ 'main', 'release/v*' ]
 
 jobs:
   check:

.github/workflows/publish.yml

@@ -0,0 +1,43 @@
+name: Publish CI
+
+on:
+  push:
+    branches: [ 'release/v*' ]
+
+# Ensure only one publish at any given time
+concurrency: publish
+
+jobs:
+  check:
+    runs-on: ubuntu-20.04
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Check gitignore rules
+        run: .github/scripts/check-gitignore-rules.sh
+
+      - name: Setup JDK
+        id: setup-java
+        uses: actions/setup-java@v2
+        with:
+          distribution: 'temurin'
+          java-version: '11'
+          cache: 'gradle'
+
+      - name: Setup gradle properties
+        run: |
+          cat .github/env/${{ runner.os }}/gradle.properties >> gradle.properties
+          echo >> gradle.properties
+          echo "org.gradle.java.installations.paths=${{ steps.setup-java.outputs.path }}" >> gradle.properties
+          cat gradle.properties
+
+      - name: Publish
+        # Note: even though we specify org.gradle.parallel=false in our CI gradle.properties, we want to be explicit
+        # here about no parallelism to ensure we don't create disjointed staging repositories.
+        run: ./gradlew --no-parallel publish
+        env:
+          ORG_GRADLE_PROJECT_ossrhUsername: ${{ secrets.SONATYPE_USERNAME }}
+          ORG_GRADLE_PROJECT_ossrhPassword: ${{ secrets.SONATYPE_PASSWORD }}
+          ORG_GRADLE_PROJECT_signingKey: ${{ secrets.CI_AT_DEEPHAVEN_KEY }}
+          ORG_GRADLE_PROJECT_signingPassword: ${{ secrets.CI_AT_DEEPHAVEN_PASSWORD }}