First cut at actions for dependency-graph

- Dependency graph init-script references published version of plugin jar.
- `dependency-graph-generate` action will:
     - Provision Gradle if required
     - Execute Gradle with dependency-graph plugin to generate graph JSON
     - Upload dependency-graph JSON file as workflow artifact
- `dependency-graph-submit` action will:
    - Download dependency-graph JSON artifact
    - Submit the graph via the GitHub dependency submission API

src/dependency-graph-generate.ts

@@ -0,0 +1,24 @@
+import * as core from '@actions/core'
+
+import * as provisioner from './provision'
+import * as dependencyGraph from './dependency-graph'
+
+/**
+ * The main entry point for the action, called by Github Actions for the step.
+ */
+export async function run(): Promise<void> {
+    try {
+        // Download and install Gradle if required
+        const executable = await provisioner.provisionGradle()
+
+        // Generate and upload dependency graph artifact
+        await dependencyGraph.generateDependencyGraph(executable)
+    } catch (error) {
+        core.setFailed(String(error))
+        if (error instanceof Error && error.stack) {
+            core.info(error.stack)
+        }
+    }
+}
+
+run()