Update path syntax for Express

It seems that * matches a literal * now, so we have to use a regular
expression.

Parentheses around a parameter no longer works (it causes it to match on
the parameter name literally) and I am not sure why we had it anyway as
it had no effect previously.

Matching with a leading / does not appear to work either, but we do not
need the leading / anyway since the proxy logic was changed to use the
whole path.  Consequently it will never be / anymore from what I can
tell but I left that check in just in case.  I turned it into a named
parameter as well, because that seems better.

test/unit/node/proxy.test.ts

@@ -199,7 +199,7 @@ describe("proxy", () => {
   })
 
   it("should proxy non-ASCII", async () => {
-    e.get("*", (req, res) => {
+    e.get(/.*/, (req, res) => {
       res.json("ほげ")
     })
     codeServer = await integration.setup(["--auth=none"], "")
@@ -211,7 +211,7 @@ describe("proxy", () => {
 
   it("should not double-encode query variables", async () => {
     const spy = jest.fn()
-    e.get("*", (req, res) => {
+    e.get(/.*/, (req, res) => {
       spy([req.originalUrl, req.query])
       res.end()
     })