Secure Store for Private Info for Providers

[rootedbox]

Validations

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

Problem

Currently providers and configs don't have a way to store secure info.

Solution

Look for best practices on how others have implemented this on other VSC and JetBrains plugins. Then implement.

[rootedbox]

https://code.visualstudio.com/api/references/vscode-api#SecretStorage