put logs and curtin config in installed system at /var/log/installer

subiquity/models/subiquity.py

@@ -87,6 +87,8 @@ class SubiquityModel:
             'install': {
                 'target': target,
                 'unmount': 'disabled',
+                'save_install_config': '/var/log/installer/curtin-install-cfg.yaml',
+                'save_install_logs': '/var/log/installer/curtin-install.log',
                 },
 
             'partitioning_commands': {