g.region: revision of output formats

[echoix]

There are print flags that add information (-l, -e, -c, -n, -3, -b). I don't think all of them are printed in flat format on 1 line with this PR yet.

I think that falls into the general revision of all output formats below.

I agree the -f flag should stand on its own in the same way you don't have to use -g flag together with -p flag.

I also expect that. -g usually means "key=value" line by line in other tools and there are no modifications to the format.

Ultimately we could introduce some kind of format method to include json format and get rid of all these flags?

That would be ideal.

Originally posted by @wenzeslaus in https://github.com/OSGeo/grass/pull/3216#issuecomment-1798690010