Print stderr when running a command just like vim does

[pmnoxx]

I noticed that whenever try to run a local command: ":! something" only stdout gets printed.

In vim/nvim both stderr and stdout get printed. We can fix this with this PR.

TODO:

• Test that the stderr is printed
• Test that colors are properly stripped from the output.

[pmnoxx]

I checked, now I get a nice readable output after colors get stripped:

:!pg a %

2022-01-02T16:09:29.671516Z  INFO play_ground::imports_analyzer: crate::cmd -> 1
2022-01-02T16:09:29.671530Z  INFO play_ground::imports_analyzer: crate::custom_layer::CustomLayer -> 1
2022-01-02T16:09:29.671534Z  INFO play_ground::imports_analyzer: anyhow::Error -> 3
2022-01-02T16:09:29.671537Z  INFO play_ground::imports_analyzer: reqwest::header -> 4
2022-01-02T16:09:29.671540Z  INFO play_ground::imports_analyzer: std::env -> 3
2022-01-02T16:09:29.671543Z  INFO play_ground::imports_analyzer: std::fs -> 1
2022-01-02T16:09:29.671545Z  INFO play_ground::imports_analyzer: std::io -> 4
2022-01-02T16:09:29.671547Z  INFO play_ground::imports_analyzer: std::path -> 1
2022-01-02T16:09:29.671550Z  INFO play_ground::imports_analyzer: std::process -> 1
2022-01-02T16:09:29.671553Z  INFO play_ground::imports_analyzer: tracing::Level -> 3 / 4 indirect=1
2022-01-02T16:09:29.671556Z ERROR play_ground::imports_analyzer: x1=3 x2=4

[AlexPl292]

Great, thank you for the contribution!

[AlexPl292]

Hi @pmnoxx ! Could you please take a look at this discussion so we can use your change under the new MIT license? Thank you!

#542