feat: Add short pathSeparator alias

Visual Studio Code has a predefined variable ${pathSeparator} that
represents the path separator on the current platform. It has
a shorter alias ${/}.

This commit adds support for the short alias to the extension
path handler.

Author: pda0

src/utils/variable.ts

@@ -16,6 +16,7 @@ export async function parseVariables(strList: string[], activeFile?: Uri) {
     > = new Map([
         ['${userHome}', homedir()],
         ['${pathSeparator}', path.sep],
+        ['${/}', path.sep],
     ]);
 
     const { workspaceFolders } = vscode.workspace;