Add Support for Fetching API Keys from 1Password

[sghuang19]

Validations

• I believe this is a way to improve. I'll try to join the Continue Discord for questions
• I'm not able to find an open issue that requests the same enhancement

Problem

Currently api keys have to be hardcoded in config.json.

Solution

Support 1Password secret reference syntax in config.json api keys:

{
  models: {
    myModel: {
      apiKey: "op://development/sliliconflow/apiKey"
    }
  }
}

which will invoke 1Password to fetch secrets.