dvc plots show: Allow for setting output directory via config or dvc.yaml

[mseflek]

Currently the output directory (default dvc_plots/) for the HTML file produced by dvc plots show can only be defined via the command's -o flag. It would be great if it could be set via dvc.yaml or the config files so that running dvc plots show automatically saves the file in a predefined place. This would make it more seamless to use in projects with a well-defined directory structure.

[dberenbaum]

@pared @daavoo How hard do you think this would be? Would it make a good first issue?

[daavoo]

@pared @daavoo How hard do you think this would be?

I think not much, but probably there are some gotchas.

Would it make a good first issue?

Maybe not, because of the gotchas.

[pared]

I don't see any bigger problems at first sight. We already have a config section for plots, there is only one actual line addressing dvc_plots, in plots command code. We can access the repo there too... there might be a problem with no repo situation, but AFAIR getting config there will result in an empty dict.

[pared]

I would consider it for first issue.