Support pipeline matrix feature

Feature request

Support all usual commands in case of tekton matrix.

Use case

Interact with Tekton pipelines that make use of matrix.

UI Example

I think the basic support would be make the logs command work. The current behaviour lists all tasks but the logs are only those of the first taskrun from the matrix.

$ tkn pr describe matrixed-pr-hl56m
Name:                  matrixed-pr-hl56m
Namespace:             default
Service Account:       default
Timeout(Deprecated):   1h0m0s
Labels:
 tekton.dev/pipeline=matrixed-pr-hl56m

🌡️  Status

STARTED         DURATION   STATUS
5 minutes ago   31s        Succeeded

🗂  Taskruns

 NAME                                               TASK NAME                    STARTED         DURATION   STATUS
 ∙ matrixed-pr-hl56m-platforms-and-browsers-dag-4   platforms-and-browsers-dag   5 minutes ago   7s         Succeeded
 ∙ matrixed-pr-hl56m-platforms-and-browsers-dag-5   platforms-and-browsers-dag   5 minutes ago   15s        Succeeded
 ∙ matrixed-pr-hl56m-platforms-and-browsers-dag-0   platforms-and-browsers-dag   5 minutes ago   10s        Succeeded
 ∙ matrixed-pr-hl56m-platforms-and-browsers-dag-1   platforms-and-browsers-dag   5 minutes ago   10s        Succeeded
 ∙ matrixed-pr-hl56m-platforms-and-browsers-dag-2   platforms-and-browsers-dag   5 minutes ago   11s        Succeeded
 ∙ matrixed-pr-hl56m-platforms-and-browsers-dag-3   platforms-and-browsers-dag   5 minutes ago   12s        Succeeded
 ∙ matrixed-pr-hl56m-get-platforms                  get-platforms                5 minutes ago   8s         Succeeded
 ∙ matrixed-pr-hl56m-get-browsers                   get-browsers                 5 minutes ago   15s        Succeeded

But in the logs:

$ tkn pr logs matrixed-pr-hl56m -f
[get-platforms : echo] linuxmacwindows

[get-browsers : echo] chromesafarifirefox

[platforms-and-browsers-dag : echo] windows and chrome

It might be nice to highlight the matrix better in the CLI view as well, for instance by visually grouping TaskRuns that belong to a matrix and which TaskRun is associated with this tuple of inputs.

Start with the tkn pr logs and tkn pr describe commands and read the linked Tekton matrix documentation. Reproduce the example pipeline, then trace how matrix TaskRuns are selected for logs and displayed in the CLI. Done means logs include all matrix TaskRuns and the describe view makes matrix groupings or input tuples clear.