Refactor slow to type check expression (#8565)

### Motivation:

An expression in `SwiftRunCommand` was taking almost 2 seconds to type
check on my M4 MacBook.

### Modifications:

Break it out in to multiple, faster to type check expressions. 

### Result:

This brings each individual expression down to under 80ms to check.

This was diagnosed with:

```
swift build \
  -Xswiftc -Xfrontend -Xswiftc -warn-long-function-bodies=80 \
  -Xswiftc -Xfrontend -Xswiftc -warn-long-expression-type-checking=80
```

Author: plemarquand

Sources/Commands/SwiftRunCommand.swift

@@ -274,7 +274,8 @@ public struct SwiftRunCommand: AsyncSwiftCommand {
         // If the executable is implicit, search through root products.
         let rootExecutables = graph.rootPackages
             .flatMap { $0.products }
-            .filter { $0.type == .executable || $0.type == .snippet }
+            // The type checker slows down significantly when ProductTypes arent explicitly typed.
+            .filter { $0.type == ProductType.executable || $0.type == ProductType.snippet }
             .map { $0.name }
 
         // Error out if the package contains no executables.