feat(frontend) Remove "credentials" from export & import of agents

[Bentlybro]

Changes 🏗️

This is for Credential ID Exports into Agent JSON #8919

I have added a new function removeCredentials into utils.ts which will go through and look for any "credentials" that are in the JSON during a agent export, this will then remove them and let the user download the file.

I have also added the same function to the importing of agents for old agents that where exported that still contain the credentials, this means that old agents can be imported with out breaking/causing issues.

When I say it looks for credentials I dont mean actual credentials like api keys them self, in the JSON that is exported it contains the following, this needs removing

"credentials": {
  "id": "6767232a-3407-4c34-85a3-6887d4969f0c",
  "title": "Anthropic Toran",
  "provider": "anthropic",
  "type": "api_key"
},

If there is a better way to go about this let me know!

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[Swiftyos]

This is a good idea