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/completionsObservableWorkspace.ts

@@ -0,0 +1,10 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+import { VSCodeWorkspace } from '../../../../inlineEdits/vscode-node/parts/vscodeWorkspace';
+import { ICompletionsObservableWorkspace } from '../../lib/src/completionsObservableWorkspace';
+
+export class CompletionsObservableWorkspace extends VSCodeWorkspace implements ICompletionsObservableWorkspace {
+	declare _serviceBrand: undefined;
+}