Add tokenization and context provider API types

- Implemented window delineation tests for indentation-based tokenization.
- Created tokenizer module with various tokenization strategies including TTokenizer and ApproximateTokenizer.
- Added type definitions for authentication parameters and code citation notifications.
- Introduced context provider API for extensions to supply additional context items to Copilot.
- Defined core types and schemas for position and range.
- Established status types for agent status management in IDEs.

completions-sample-code/extension/src/copilotPanel/copilotSuggestionsPanel.ts

@@ -0,0 +1,53 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { TextDocument, WebviewPanel } from 'vscode';
+import { IVSCodeExtensionContext } from '../../../../../../platform/extContext/common/extensionContext';
+import { BaseSuggestionsPanel, SolutionContent, WebviewMessage } from '../panelShared/baseSuggestionsPanel';
+import { PanelCompletion } from './common';
+import { CopilotSuggestionsPanelManager } from './copilotSuggestionsPanelManager';
+import { copilotPanelConfig } from './panelConfig';
+
+export interface CopilotSolutionsMessage {
+	command: 'solutionsUpdated';
+	solutions: SolutionContent[];
+	percentage: number;
+}
+
+export class CopilotSuggestionsPanel extends BaseSuggestionsPanel<PanelCompletion> {
+	constructor(
+		webviewPanel: WebviewPanel,
+		document: TextDocument,
+		suggestionsPanelManager: CopilotSuggestionsPanelManager,
+		@IVSCodeExtensionContext contextService: IVSCodeExtensionContext,
+	) {
+		super(webviewPanel, document, suggestionsPanelManager, copilotPanelConfig, contextService);
+	}
+
+	protected renderSolutionContent(item: PanelCompletion, baseContent: SolutionContent): SolutionContent {
+		// Copilot panel just returns the base content without modifications
+		return baseContent;
+	}
+
+	protected createSolutionsMessage(content: SolutionContent[], percentage: number): CopilotSolutionsMessage {
+		return {
+			command: 'solutionsUpdated',
+			solutions: content,
+			percentage,
+		};
+	}
+
+	protected override async handleCustomMessage(message: WebviewMessage): Promise<boolean> {
+		switch (message.command) {
+			case 'acceptSolution': {
+				const solution = this.items()[message.solutionIndex];
+				await this.acceptSolution(solution, true);
+				return Promise.resolve(true);
+			}
+			default:
+				return Promise.resolve(false);
+		}
+	}
+}