Option to set backend for delve

Author: ramya-rao-a

package.json

@@ -328,6 +328,15 @@
                 "type": "string",
                 "description": "Absolute path to a file containing environment variable definitions.",
                 "default": "${workspaceRoot}/.env"
+              },
+              "backend": {
+                "type": "string",
+                "enum": [
+                  "default",
+                  "native",
+                  "lldb"
+                ],
+                "description": "Backend used by delve. Only available in delve version 0.12.2 and above."
               }
             }
           }

src/debugAdapter/goDebug.ts

@@ -140,6 +140,7 @@ interface LaunchRequestArguments extends DebugProtocol.LaunchRequestArguments {
 	trace?: boolean|'verbose';
 	/** Optional path to .env file. */
 	envFile?: string;
+	backend?: string;
 }
 
 process.on('uncaughtException', (err: any) => {
@@ -283,11 +284,13 @@ class Delve {
 			if (launchArgs.init) {
 				dlvArgs = dlvArgs.concat(['--init=' + launchArgs.init]);
 			}
+			if (launchArgs.backend) {
+				dlvArgs = dlvArgs.concat(['--backend=' + launchArgs.backend]);
+			}
 			if (launchArgs.args) {
 				dlvArgs = dlvArgs.concat(['--', ...launchArgs.args]);
 			}
 
-
 			this.debugProcess = spawn(dlv, dlvArgs, {
 				cwd: dlvCwd,
 				env,