Allow hiding warnings in Scarb output

[DelevoXDG]

Add no-warnings verbosity option, available as --no-warnings flag or env var setting

Closes #1660

[maciektr]

This can be

Suggested change

	NoWarnings,
	Error,

Indicating that it will print errors but not warnings

[DelevoXDG]

That was my initial thought too, but we have some outputs that aren’t warnings or errors, like:

    ws.config()ui().print(Status::new("Packaging", &pkg_id.to_string()));

I figured we probably want to keep these messages and only mute warnings, so NoWarnings seemed more fitting.

[maciektr]

Yes, I would still use ERROR as it's more customary

[DelevoXDG]

Are you sure it's more customary? It might make sense as environment variable setting, but, unlike --quiet, --verbose and --no-warnings, --error as a flag imo doesn't seem like it is directly related to verbosity, and reading docs will be required to understand what it actually does.

[maciektr]

Why we do not need to change this tests, if we do:

impl From<VerbositySpec> for Verbosity {
    fn from(spec: VerbositySpec) -> Self {
        match spec.integer_verbosity() {
            v if v < -1 => Verbosity::Quiet,
            -1 => Verbosity::NoWarnings,

Shouldn't quiet=1, verbose=0 be the new one then? 🤔

[DelevoXDG]

I'm not sure I understand, quiet=1, verbose=0 shouldn't produce any different verbosity level than before? That's not something this PR aims to change 🤔

[maciektr]

But you are changing impl From<VerbositySpec> for Verbosity which is used to parse it, right?

[DelevoXDG]

I am, but only to create conditions for setting NoWarnings verbosity level, without affecting impact of --quiet and --verbose flags on settings their respectful verbosity level.

[maciektr]

Why check twice? 🤔
Can we do

if self.no_warnings {
    return -1;
}

at the beginning of this function, and avoid changing anything else?

[DelevoXDG]

Yep, I initially added the check at the beginning of the function, but later thought setting int_level first is just more in line with existing approach. Removed the extra check 👍🏻