src/debugAdapter: send continued event on step requests

With VS Code 1.58, there was a change to the debugging UI
that automatically auto expands at least one thread's call
stack. The next, step in, and step out requests do not automatically
imply that all threads were resumed. In Go, we cannot
resume a single goroutine. We can provide this info in DAP
by sending a continued event before sending the response
to the request.

Fixes golang/vscode-go#1617
Fixes golang/vscode-go#1647

Change-Id: I60cde9ead1c7b603e4dd94346e6695926923fbd9
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/338194
Trust: Suzy Mueller <suzmue@golang.org>
Run-TryBot: Suzy Mueller <suzmue@golang.org>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Polina Sokolova <polina@google.com>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
diff --git a/src/debugAdapter/goDebug.ts b/src/debugAdapter/goDebug.ts
index 8f62265..f7d3311 100644
--- a/src/debugAdapter/goDebug.ts
+++ b/src/debugAdapter/goDebug.ts
@@ -19,6 +19,7 @@
 import * as path from 'path';
 import * as util from 'util';
 import {
+	ContinuedEvent,
 	DebugSession,
 	ErrorDestination,
 	Handles,
@@ -1779,6 +1780,8 @@
 			this.debugState = state;
 			this.handleReenterDebug('step');
 		});
+		// All threads are resumed on a next request
+		this.sendEvent(new ContinuedEvent(1, true));
 		this.sendResponse(response);
 		log('NextResponse');
 	}
@@ -1802,6 +1805,8 @@
 			this.debugState = state;
 			this.handleReenterDebug('step');
 		});
+		// All threads are resumed on a step in request
+		this.sendEvent(new ContinuedEvent(1, true));
 		this.sendResponse(response);
 		log('StepInResponse');
 	}
@@ -1825,6 +1830,8 @@
 			this.debugState = state;
 			this.handleReenterDebug('step');
 		});
+		// All threads are resumed on a step out request
+		this.sendEvent(new ContinuedEvent(1, true));
 		this.sendResponse(response);
 		log('StepOutResponse');
 	}