feat: define Agent . config, mTLS config

### Area / component

CLI (cds)

### Problem statement

Define spec and implement the config storing mTLS to communicate to CDS CLI

### Proposed solution

Define spec and implement the config storing mTLS to communicate to CDS CLI

### Alternatives considered

_No response_

### Scope / impact

_No response_

### Contribution

- [ ] I’m willing to help implement this feature.