Consider simplifying log function interface

There is no real difference between:

```ts
log.info({time: 1}, 'foo');
```

and

```ts
log.child({time: 1}).info('foo');
```

If we dropper the former API interface, it would make it easier to avoid mistakes such as [attempting to pass context as printf parameters](https://github.com/gajus/roarr/commit/a7376a9be6f25d05ea8dd194eae2e112c838ab56).

Great suggestion by @mikeroelens.

The only concern here is that it is a major breaking change with no easy way to add backwards compatibility. I doubt it will be implemented due to the latter reason, but worth considering how we could promote this pattern more.

No file, test, or entry point is identified. Start by locating the existing log.info context-argument and log.child APIs, then determine whether the breaking interface change or documentation and promotion of the child pattern is intended; done is not defined beyond resolving that design decision.

Written by the indexing model from the issue text.