s3:HardwareInfo was removed recently. Users having that admin action
stored in the backend will have an issue starting the server.
To fix this, we need to avoid returning an error in Marshal/Unmarshal
when they encounter an invalid action and validate only in specific
location.
Currently the validation is done and in ParseConfig().
This PR introduces two new features
- AWS STS compatible STS API named AssumeRoleWithClientGrants
```
POST /?Action=AssumeRoleWithClientGrants&Token=<jwt>
```
This API endpoint returns temporary access credentials, access
tokens signature types supported by this API
- RSA keys
- ECDSA keys
Fetches the required public key from the JWKS endpoints, provides
them as rsa or ecdsa public keys.
- External policy engine support, in this case OPA policy engine
- Credentials are stored on disks
