Enable dnd and copy paste apis in scm input

For microsoft#209460

Enables dropping or pasting a file from the vscode/system explorer into the scminput to insert the file name. Currently nothing happens when you try this

In the future will also allow extensions to hook into these apis

src/vs/editor/contrib/dropOrPasteInto/browser/postEditWidget.ts

@@ -164,6 +164,9 @@ export class PostEditWidgetManager<T extends DocumentPasteEdit | DocumentOnDropE
 		}
 
 		const resolvedEdit = await resolve(edit, token);
+		if (token.isCancellationRequested) {
+			return;
+		}
 
 		const combinedWorkspaceEdit = createCombinedWorkspaceEdit(model.uri, ranges, resolvedEdit);
 
@@ -174,6 +177,7 @@ export class PostEditWidgetManager<T extends DocumentPasteEdit | DocumentOnDropE
 			options: { description: 'paste-line-suffix', stickiness: TrackedRangeStickiness.AlwaysGrowsWhenTypingAtEdges }
 		}]);
 
+		this._editor.focus();
 		let editResult: IBulkEditResult;
 		let editRange: Range | null;
 		try {
@@ -183,6 +187,10 @@ export class PostEditWidgetManager<T extends DocumentPasteEdit | DocumentOnDropE
 			model.deltaDecorations(editTrackingDecoration, []);
 		}
 
+		if (token.isCancellationRequested) {
+			return;
+		}
+
 		if (canShowWidget && editResult.isApplied && edits.allEdits.length > 1) {
 			this.show(editRange ?? primaryRange, edits, async (newEditIndex) => {
 				const model = this._editor.getModel();

src/vs/editor/contrib/snippet/browser/snippetController2.ts

@@ -331,7 +331,7 @@ registerEditorCommand(new CommandCtor({
 	handler: ctrl => ctrl.next(),
 	kbOpts: {
 		weight: KeybindingWeight.EditorContrib + 30,
-		kbExpr: EditorContextKeys.editorTextFocus,
+		kbExpr: EditorContextKeys.textInputFocus,
 		primary: KeyCode.Tab
 	}
 }));
@@ -341,7 +341,7 @@ registerEditorCommand(new CommandCtor({
 	handler: ctrl => ctrl.prev(),
 	kbOpts: {
 		weight: KeybindingWeight.EditorContrib + 30,
-		kbExpr: EditorContextKeys.editorTextFocus,
+		kbExpr: EditorContextKeys.textInputFocus,
 		primary: KeyMod.Shift | KeyCode.Tab
 	}
 }));
@@ -351,7 +351,7 @@ registerEditorCommand(new CommandCtor({
 	handler: ctrl => ctrl.cancel(true),
 	kbOpts: {
 		weight: KeybindingWeight.EditorContrib + 30,
-		kbExpr: EditorContextKeys.editorTextFocus,
+		kbExpr: EditorContextKeys.textInputFocus,
 		primary: KeyCode.Escape,
 		secondary: [KeyMod.Shift | KeyCode.Escape]
 	}