Adding Execution Plan Editor to ADS (#18696)

* Pushing Execution Plan Editor

* Renaming class
Handling error

* Awaiting for handlers to be registered

* Addressing some PR comments

* Fixing return type for provider

* Fixing editor id and removing unnecessary overrides

* Adding a namespace

* adding execution plan namespace

* Adding protocol comment

* Fixing if logic

* Fixing error message

* Cleaning up code

* cleanup code

* Adding help comments

* Fixing method call

* Using path.ts to get the base file name

* converting to lambda functions

* Adding comment for run action

* Fixing pr comments

* Fixing editor label

* Fixing doc comments

* Adding some more comments

* Fixign branding in comments

src/sql/workbench/contrib/executionPlan/common/executionPlanInput.ts

@@ -0,0 +1,60 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import * as path from 'vs/base/common/path';
+import { URI } from 'vs/base/common/uri';
+import { EditorInput } from 'vs/workbench/common/editor/editorInput';
+import { EditorModel } from 'vs/workbench/common/editor/editorModel';
+import { ITextFileService } from 'vs/workbench/services/textfile/common/textfiles';
+
+export class ExecutionPlanInput extends EditorInput {
+
+	public static ID: string = 'workbench.editorinputs.executionplan';
+	public static SCHEMA: string = 'executionplan';
+
+	private _content?: string;
+
+	constructor(
+		private _uri: URI,
+		@ITextFileService private readonly _fileService: ITextFileService,
+	) {
+		super();
+	}
+
+	override get typeId(): string {
+		return ExecutionPlanInput.ID;
+	}
+
+	public override getName(): string {
+		return path.basename(this._uri.fsPath);
+	}
+
+	public get content(): string | undefined {
+		return this._content;
+	}
+
+	public getUri(): string {
+		return this._uri.toString();
+	}
+
+	public getFileExtension(): string {
+		return path.extname(this._uri.fsPath);
+	}
+
+	public supportsSplitEditor(): boolean {
+		return false;
+	}
+
+	public override async resolve(refresh?: boolean): Promise<EditorModel | undefined> {
+		if (!this._content) {
+			this._content = (await this._fileService.read(this._uri, { acceptTextOnly: true })).value;
+		}
+		return undefined;
+	}
+
+	get resource(): URI | undefined {
+		return undefined;
+	}
+}