New global flags:
* `--log-file FILE`: can be literal `stdout`, `stderr`, or a file name (default `stderr`)
* `--log-level LEVEL`: can be `error`, `warn`, `info`, `debug`, `trace`, or `disabled` (default `disabled`)
* `--log-format TYPE`: can be `text` or `json` (default `text`)
New functions in the `log` package take a `context.Context` and retrieve
the logger from said context.
Because we carry the logger in a context, adding
[attributes](https://pkg.go.dev/golang.org/x/exp/slog#hdr-Attrs_and_Values)
to the logger can be done as follows:
```go
ctx = log.NewContext(ctx, log.GetLogger(ctx).With("foo", "bar"))
```
Pieter Noordhuis