Fix inconsistent code action edit property names

**Bug**
We were using `edits` in some places and `edit` in others. This broke some use patterns for code actions

src/vs/workbench/api/node/extHost.protocol.ts

@@ -630,7 +630,7 @@ export interface WorkspaceEditDto {
 
 export interface CodeActionDto {
 	title: string;
-	edits?: WorkspaceEditDto;
+	edit?: WorkspaceEditDto;
 	diagnostics?: IMarkerData[];
 	command?: modes.Command;
 }

src/vs/workbench/api/node/extHostApiCommands.ts

@@ -408,7 +408,7 @@ export class ExtHostApiCommands {
 				} else {
 					const ret = new types.CodeAction(
 						codeAction.title,
-						typeConverters.WorkspaceEdit.to(codeAction.edits)
+						typeConverters.WorkspaceEdit.to(codeAction.edit)
 					);
 					return ret;
 				}

src/vs/workbench/api/node/extHostLanguageFeatures.ts

@@ -313,7 +313,7 @@ class CodeActionAdapter {
 						title: candidate.title,
 						command: candidate.command && this._commands.toInternal(candidate.command),
 						diagnostics: candidate.diagnostics && candidate.diagnostics.map(DiagnosticCollection.toMarkerData),
-						edits: candidate.edit && TypeConverters.WorkspaceEdit.from(candidate.edit),
+						edit: candidate.edit && TypeConverters.WorkspaceEdit.from(candidate.edit),
 					});
 				}
 			}

src/vs/workbench/api/node/extHostTypes.ts

@@ -814,13 +814,13 @@ export class CodeAction {
 
 	command?: vscode.Command;
 
-	edits?: WorkspaceEdit;
+	edit?: WorkspaceEdit;
 
 	dianostics?: Diagnostic[];
 
-	constructor(title: string, edits?: WorkspaceEdit) {
+	constructor(title: string, edit?: WorkspaceEdit) {
 		this.title = title;
-		this.edits = edits;
+		this.edit = edit;
 	}
 }