Feature request: re-order output columns without explicitly defining them

[jwuerzinger]

Following up on #388, it would be really nice to add an option to reorder columns without having to explicitly define colours etc.

I.e. changing sth like this:

 2021-12-25 00:08:19 [debug    ] running in verbose mode        [myapp]

into e.g.

 2021-12-25 00:08:19 [myapp] [debug    ] running in verbose mode

with e.g. something like:

processors=structlog.get_config()["processors"]
processors[-1].reorder_columns([0, 3, 1, 2])
structlog.configure( processors=processors )

[hynek]

I guess you can do that by mangling processors[-1]._columns for now.