Updates lint output to print detail instead of description

[daghack]

Currently, the PrintLintViolations output warning text includes the static description of the lint rule, rather than the formatted text message that often includes context specific to a given instance of rule violation.

This updates PrintLintViolations to print out the formatted lint message instead. Below is an instance where you can see the difference in the types of output.

Current:

UndefinedVar - https://docs.docker.com/go/dockerfile/rule/undefined-var/
Variables should be defined before their use
Dockerfile:3
--------------------
   1 |     FROM alpine
   2 | >>> ENV PATH=$PAHT:/foo
   3 |
--------------------

New:

UndefinedVar - https://docs.docker.com/go/dockerfile/rule/undefined-var/
Usage of undefined variable '$PAHT' (did you mean $PATH?)
Dockerfile:3
--------------------
   1 |     FROM alpine
   2 | >>> ENV PATH=$PAHT:/foo
   3 |
--------------------

[tonistiigi]

We probably need to go over these more in some follow-ups. Looking at the example I would say in that case both messages are useful. One is pointing out a mistake and suggesting a fix and the other is describing what the general rule for the validation is. I guess for some of the rules the separation isn't quite as obvious and we don't show both to avoid duplication. In that case I think we can define what rules benefit from multiple fields and keep it hidden/empty if extra field does not add additional context. We can also define more clearly how the verbosity changes with --debug.

[tonistiigi]

This removes the line position from the default output for build warnings (without --debug).

Before:

 1 warning found (use --debug to expand):
 - UndefinedVar: Usage of undefined variable '$PAHT' (did you mean $PATH?) (line 2)

Now:

 1 warning found (use --debug to expand):
 - UndefinedVar: Usage of undefined variable '$PAHT' (did you mean $PATH?)

[daghack]

Updated to return the line number to the buildkit progress stream and docker --debug output.

[crazy-max]

@tonistiigi Is it needed to have the line number in progress as we already have this information in?:

Usage of undefined variable '$PAHT' (did you mean $PATH?)
Dockerfile:3
--------------------
   1 |     FROM alpine
   2 | >>> ENV PATH=$PAHT:/foo
   3 |
--------------------

Mostly looking at docker/actions-toolkit#365 (comment)

[tonistiigi]

That is only with --debug. By default there is no source code view.

[tonistiigi]

I agree that this is not needed for example in your github actions excerpt. It should probably be added in buildx side for views that need it, not inside the string here.