[MNG-7849] Improvement in settings/server configuration for http transport

**[Slawomir Jaranowski](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=slawekjaranowski)** opened **[MNG-7849](https://issues.apache.org/jira/browse/MNG-7849?redirect=false)** and commented

When we use configuration like: `server/configuration/httpConfiguration/all/connectionTimeout` we always have a warning:

```
[WARNING] Settings for server serverId uses legacy format
```

Such warning should be more descriptive.

Even we use `-Dmaven.resolver.transport=wagon` warning is still present - check if should be

We can also map `server/configuration//usePreemptive` to new value with native transport - many users can use it ... but now don't know that no working any more.

We can consider if other internal options which support serverId should be mapped in `server/configuration`

We can also consider to extends settings model with transport configuration - instead using
`configuration` which can be anything and is not validate.

---

**Issue Links:**
- [MNG-7850](https://issues.apache.org/jira/browse/MNG-7850) Artifact Resolver config is ignored

- [MRESOLVER-426](https://issues.apache.org/jira/browse/MRESOLVER-426) Move some HTTP configuration properties from transport-http