Persist provider name and model config in the session

[wpfleger96]

Summary

Building off #5399, this PR enables provider name/model config persistence by storing the configs in the Session struct. Now if a user resumes a previous session with --resume, the previous session's provider and model config will be automatically reloaded instead of defaulting to the provider/model from global config.

Type of Change

• [x] Feature
• [ ] Bug fix
• [ ] Refactor / Code quality
• [ ] Performance improvement
• [ ] Documentation
• [ ] Tests
• [ ] Security fix
• [ ] Build / Release
• [ ] Other (specify below)

Testing

Manually tested

Related Issues

Fixes #5358