Save files before starting AutoBuild (#13649)

buildroot/share/vscode/AutoBuildMarlin/extension.js

 
   var NEXT_TERM_ID = 1;
   var pio_build     = vscode.commands.registerCommand('piobuild',     function () {
+    vscode.commands.executeCommand('workbench.action.files.saveAll');
     const terminal = vscode.window.createTerminal(`AB Build #${NEXT_TERM_ID++}`);
     terminal.show(true);
     terminal.sendText("python buildroot/share/atom/auto_build.py build");
     terminal.sendText("python buildroot/share/atom/auto_build.py clean");
   });
   var pio_upload    = vscode.commands.registerCommand('pioupload',    function () {
+    vscode.commands.executeCommand('workbench.action.files.saveAll');
     const terminal = vscode.window.createTerminal(`AB Upload #${NEXT_TERM_ID++}`);
     terminal.show(true);
     terminal.sendText("python buildroot/share/atom/auto_build.py upload");
   });
   var pio_traceback = vscode.commands.registerCommand('piotraceback', function () {
+    vscode.commands.executeCommand('workbench.action.files.saveAll');
     const terminal = vscode.window.createTerminal(`AB Traceback #${NEXT_TERM_ID++}`);
     terminal.show(true);
     terminal.sendText("python buildroot/share/atom/auto_build.py traceback");