GitHub Proxy: Given a directory, GitHub Proxy should return a zip file containing just that directory

[juanmaguitar]

For example, the expected behaviour for this feature would be that a link like this
https://github-proxy.com/proxy/?repo=WordPress/block-development-examples&branch=trunk&directory=plugins/block-dynamic-rendering-64756b
returns a zip with the content of the folder at https://github.com/WordPress/block-development-examples/tree/trunk/plugins/block-dynamic-rendering-64756b

This feature would be very useful in combination with the installPlugin step of blueprints.

cc: @adamziel @stoph

[adamziel]

@juanmaguitar I would love to have that in the short term! In a medium term, the same problem will be resolved by #1708

[adamziel]

Superseded by #1708 and #1793