fix(s3): starting a member's workspace makes its missing folder, as the member

v2.7.3's ENOCWD left a new member no web path to a first project: their
home is no workspace (EFOLDER) and a not-yet-existing folder could not
start. run-as.makeMemberFolder: mkdir -p through write-as, AS the member,
only inside their own home (never the home itself, never a host folder,
never for a member with no account). Test: server-s3-lanes.

server/routes/lanes.js

@@ -2078,7 +2078,9 @@ router.post("/:id/:action", sameOriginGuard, async (req, res) => {
           if (!fs.statSync(lane.cwd).isDirectory())
             throw Object.assign(new Error(), { code: "ENOTDIR" });
         } catch (err) {
-          if (err.code === "ENOENT" || err.code === "ENOTDIR") {
+          // A member's new project folder is made for them, as them.
+          const made = err.code === "ENOENT" && require("../lib/run-as").makeMemberFolder(lane.cwd);
+          if (!made && (err.code === "ENOENT" || err.code === "ENOTDIR")) {
             return res.status(409).json({
               error: {
                 code: "ENOCWD",