mgr: backward compatibility for module management
Follow up on 3abc253fec
The structure had even changed within `luminous` release.
It was first:
```
{
"enabled_modules": [
"balancer",
"dashboard",
"restful",
"status"
],
"disabled_modules": [
"influx",
"localpool",
"prometheus",
"selftest",
"zabbix"
]
}
```
Then it changed for:
```
{
"enabled_modules": [
"status"
],
"disabled_modules": [
"balancer",
"dashboard",
"influx",
"localpool",
"prometheus",
"restful",
"selftest",
"zabbix"
]
}
```
and finally:
```
{
"enabled_modules": [
"status"
],
"disabled_modules": [
{
"name": "balancer",
"can_run": true,
"error_string": ""
},
{
"name": "dashboard",
"can_run": true,
"error_string": ""
}
]
}
```
Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>
36942af698