perf(cli): faster standalone executable determination (#22717)

This was showing up on the flamegraph.

```
14:54 $ hyperfine -S none --warmup 25 '/tmp/deno run /tmp/empty.js' 'target/release/deno run /tmp/empty.js'
Benchmark 1: /tmp/deno run /tmp/empty.js
  Time (mean ± σ):      17.2 ms ±   4.7 ms    [User: 11.2 ms, System: 4.0 ms]
  Range (min … max):    15.1 ms …  72.9 ms    172 runs
 
  Warning: Statistical outliers were detected. Consider re-running this benchmark on a quiet system without any interferences from other programs. It might help to use the '--warmup' or '--prepare' options.
 
Benchmark 2: target/release/deno run /tmp/empty.js
  Time (mean ± σ):      16.7 ms ±   1.1 ms    [User: 11.1 ms, System: 4.0 ms]
  Range (min … max):    15.0 ms …  20.1 ms    189 runs
 
Summary
  'target/release/deno run /tmp/empty.js' ran
    1.03 ± 0.29 times faster than '/tmp/deno run /tmp/empty.js'
✔ ~/Documents/github/deno/deno [faster_extract|…5⚑ 23] 
```

1 files changed, 9 insertions, 4 deletions

diff --git a/cli/mainrt.rs b/cli/mainrt.rs
index 9c7ee3c5c..ae4ea727f 100644
--- a/cli/mainrt.rs
+++ b/cli/mainrt.rs
@@ -69,11 +69,16 @@ fn unwrap_or_exit<T>(result: Result<T, AnyError>) -> T {
 
 fn main() {
   let args: Vec<String> = env::args().collect();
+  let current_exe_path = current_exe().unwrap();
+  let standalone =
+    standalone::extract_standalone(&current_exe_path, args.clone());
   let future = async move {
-    let current_exe_path = current_exe().unwrap();
-    match standalone::extract_standalone(&current_exe_path, args).await {
-      Ok(Some((metadata, eszip))) => standalone::run(eszip, metadata).await,
-      Ok(None) => Err(generic_error("No archive found.")),
+    match standalone {
+      Ok(Some(future)) => {
+        let (metadata, eszip) = future.await?;
+        standalone::run(eszip, metadata).await
+      }
+      Ok(None) => Ok(()),
       Err(err) => Err(err),
     }
   };