Use more standard values for scheme constants (#153367)

This drops the `:` from the scheme constants as it was easy to misuse this

extensions/markdown-language-features/src/languageFeatures/pathCompletions.ts

@@ -9,6 +9,7 @@ import { IMdParser } from '../markdownEngine';
 import { TableOfContents } from '../tableOfContents';
 import { ITextDocument } from '../types/textDocument';
 import { resolveUriToMarkdownFile } from '../util/openDocumentLink';
+import { Schemes } from '../util/schemes';
 import { IMdWorkspace } from '../workspace';
 import { MdLinkProvider } from './documentLinks';
 
@@ -324,7 +325,7 @@ export class MdVsCodePathCompletionProvider implements vscode.CompletionItemProv
 
 	private resolvePath(root: vscode.Uri, ref: string): vscode.Uri | undefined {
 		try {
-			if (root.scheme === 'file') {
+			if (root.scheme === Schemes.file) {
 				return vscode.Uri.file(resolve(dirname(root.fsPath), ref));
 			} else {
 				return root.with({