Adding --label flag to pack builder create command

[jjbustamante]

Summary

This PR adds a new --label flag to the pack builder create command

Output

Before

The flag didn't exist before

After

New flag will look like this, when running pack builder create --help

Flags:
  -l, --label stringToString        Labels to add to the builder image, in the form of '<name>=<value>' (default [])

Running a local builder creation like

> out/pack builder create cnbs/local-builder:jammy --config builder.toml --label "foo=bar"
# then we inspect the labels
>  docker inspect cnbs/local-builder:jammy | jq '.[] | .Config.Labels' | jq .

output

{
  "foo": "bar",
  "io.buildpacks.base.distro.name": "ubuntu",
  "io.buildpacks.base.distro.version": "\"22.04\"",
  "io.buildpacks.builder.metadata": "...."
}

As we can see the label "foo=bar" was set to the builder image

Documentation

• Should this change be documented?
  • Yes, see #__
  • No

Related

Resolves #2033

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (c6dd3ce) 79.63% compared to head (bdc66d2) 79.63%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2034      +/-   ##
==========================================
+ Coverage   79.63%   79.63%   +0.01%     
==========================================
  Files         176      176              
  Lines       13199    13214      +15     
==========================================
+ Hits        10510    10522      +12     
- Misses       2020     2022       +2     
- Partials      669      670       +1     

Flag	Coverage Δ
os_linux	78.54% <80.00%> (-0.02%)	⬇️
os_macos	76.39% <80.00%> (+0.01%)	⬆️
os_windows	79.02% <80.00%> (+0.01%)	⬆️
unit	79.63% <80.00%> (+0.01%)	⬆️

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[jjbustamante]

@matejvasek could you take a look at the binaries

@natalieparellano could you give me a review here?

[matejvasek]

@jjbustamante I do not use this as a binary but rather as a library. Regardless this PR seems to work for me.