Update edgekv.js checking for token without namespace prefix

[guillaume-fr]

namespace- prefix is not added to token properties by current akamai edgekv CLI. This incompatibility leads to execution errors in EdgeWorkers that are not easy to debug.

[iwanaga]

👍
This change is backward-compatible.
I’ve also confirmed that it works without errors in my environment.

---

Let me provide additional context.

The latest edgekv.js always throws error because it expects that namespace-MY_NAMESPACE is present when the actual namespace is MY_NAMESPACE.

The current format of edgekv_tokens.js is like:

var edgekv_access_tokens = {
  "MY_NAMESPACE" : { 
    "name": "TOKEN_NAME",
    "reference" : "xxx"
  }
}