Add proxy_ca_certificate_file output to start-proxy action

Useful to avoid duplicating this across different extractors (e.g. C# and Go)

lib/start-proxy-action.js

@@ -34,6 +34,7 @@ var __importStar = (this && this.__importStar) || (function () {
 })();
 Object.defineProperty(exports, "__esModule", { value: true });
 const child_process_1 = require("child_process");
+const fs = __importStar(require("fs"));
 const path = __importStar(require("path"));
 const core = __importStar(require("@actions/core"));
 const toolcache = __importStar(require("@actions/tool-cache"));
@@ -111,6 +112,16 @@ async function runWrapper() {
         all_credentials: credentials,
         ca,
     };
+    // Try to write the certificate to disk. Some extractors may use this to populate
+    // the `SSL_CERT_FILE` environment variable.
+    try {
+        const certificatePath = path.join(actionsUtil.getTemporaryDirectory(), "codeql_package_proxy.crt");
+        fs.writeFileSync(certificatePath, ca.cert);
+        proxyConfig.ca_certificate_file = certificatePath;
+    }
+    catch (error) {
+        logger.error(`Failed to write the proxy certificate to disk: ${util.getErrorMessage(error)}`);
+    }
     // Start the Proxy
     const proxyBin = await getProxyBinaryPath();
     await startProxy(proxyBin, proxyConfig, proxyLogFilePath, logger);
@@ -154,6 +165,7 @@ async function startProxy(binPath, config, logFilePath, logger) {
         core.setOutput("proxy_host", host);
         core.setOutput("proxy_port", port.toString());
         core.setOutput("proxy_ca_certificate", config.ca.cert);
+        core.setOutput("proxy_ca_certificate_file", config.ca_certificate_file);
         const registry_urls = config.all_credentials
             .filter((credential) => credential.url !== undefined)
             .map((credential) => ({