Preventing certain fields of a span being logged with BunyanFormattingLayer

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Quick question, is it possible to configure `BunyanFormattingLayer` to prevent logging certain fields to the console?

My use case is as follows. I have a panic hook set up with [`color-eyre`](https://lib.rs/crates/color-eyre) that gives me a fancy backtrace (with colors and stuff) whenever a panic occurs in my web app. I use `tracing::error(error_report = %panic_report)` to log the fancy backtrace generated by `color-eyre` to the `BunyanFormattingLayer`. The problem is, I want these logs to **only** appear in the context of an external observability solution, such as [Jaeger](https://www.jaegertracing.io/), so **not** in the console.

So right now my panic logs in the console look like this: (without the newlines)

```json
{
"v": 0,
"name": "",
"msg": "[REQUEST - EVENT] Lazy instance has previously been poisoned",
"level": 50,
"hostname": "",
"pid": 34264,
"time": "2022-07-17T11:32:18Z",
"target": "panic_hook",
"line": 20,
"file": "",
"error_report": ""
}
```

So the extremely long backtrace is polluting my logs.

My question is: is it possible to prevent the "error_report" field from appearing in the logs, while still having it available to external observability solutions?

Start at BunyanFormattingLayer and inspect how event fields such as error_report are selected for console output while remaining available to external observability solutions. Done means determining or documenting a way to exclude that field from console logs without removing it from other outputs.

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