feat: color and plain modes for --progress flag

[PhantomInTheWire]

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update

Motivation and Context

relevant issue: #641

Adds two new modes to --progress: plain and color.

• plain: Produces simple, line-by-line text output with no ANSI escape codes. Ideal for writing to log files or environments that don’t support terminal control sequences.

• color: Similar to the existing ANSI mode but with enhanced color usage. This mode provides a more expressive visual display. If it sounds good, we could consider making it the default in this or a follow up pr.

Testing

• Tested locally
• Added/updated tests
• Added/updated docs

[saehejkang]

I don't see anything out of the ordinary on these changes, but I also don't have permissions to approve PRs. You will have to wait for a maintainer to come back to this for a ✅ .

[PhantomInTheWire]

@katiewasnothere @saehejkang what do you guys think about making color mode the default mode instead of ansi since it visually looks a lot more appealing?

[katiewasnothere]

@PhantomInTheWire From an accessibility standpoint, I think we should keep the default something without colors.

[PhantomInTheWire]

sure i guess that makes sense, can you take a look again i have refactored with the requested change @katiewasnothere

[jglogan]

what do you guys think about making color mode the default mode instead of ansi since it visually looks a lot more appealing

#915 is open for using the standard buildkit environment variables to set color choices there.

Consider filing a follow-on issue for allowing users to set a persistent default for non-build --progress using a system property value.

So far our system properties are all backed by user defaults but we've discussed internally changing this to environment variables. That would allow users to set their global defaults in an rc file or profile, and then override them on a per-terminal basis.

[PhantomInTheWire]

@jglogan sure i've opened up #935 for now so it can be discussed and worked upon later