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"))
```
Example when called from vscode (and everything is hooked up):
```
> * User-Agent: bricks/0.0.21-devel databricks-sdk-go/0.2.0 go/1.19.4 os/darwin upstream/databricks-vscode
```
This configures the user agent with the bricks version and the name of
the command being executed.
Example user agent value:
```
> * User-Agent: bricks/0.0.21-devel databricks-sdk-go/0.2.0 go/1.19.4 os/darwin cmd/sync auth/pat
```
This is a follow up for #194.
Not settled whether this should live as a top level command or hidden
under some debug scope. Either way, the ability to make arbitrary API
calls and leverage unified auth is a super useful tool.
shreyas-goenka
Pieter Noordhuis
Serge Smertin