Comment with dependency diff

[wzieba]

Description

This PR introduces comment_with_dependency_diff script that is aiming to help Android product teams to better understand what changes to the dependency tree a PR might introduce.

We use similar scripts in WooCommerce and Day One projects. I want to extend support to other projects and share the implementation between them for easier maintenance.

Additionally, this PR introduces some improvements to the script:

• comment on PR without using Gradle (so our Android apps can remove another, not really needed dependency from their codebase)
• print build environment changes as well (previously, the script was only printing runtime dependencies changes)

To see the result, please see:

• Pocket Casts: https://github.com/Automattic/pocket-casts-android/pull/2857
• Matticspace Mobile (for the case of a large diff): https://github.com/Automattic/Matticspace-Mobile/pull/67

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• [ ] I have considered if this change warrants release notes and have added them to the appropriate section in the CHANGELOG.md if necessary.

[wzieba]

Thank you @AliSoftware for the review! You raised good points. I think I've adjusted the implementation. Here are also updated tests:

• Matticspace Mobile (case with exceeding size: https://github.com/Automattic/Matticspace-Mobile/pull/67)
• Pocket Casts (casual case: https://github.com/Automattic/pocket-casts-android/pull/2857)

Both seem to still work fine.

[wzieba]

Correction, title is missing

[wzieba]

We're back on track!

https://github.com/Automattic/Matticspace-Mobile/pull/67

[AliSoftware]

I just realized that there might be more to it to compute the exact comment body length, because:

• I'm guessing GitHub counts \n as a character (i.e. comparing with the current length + length of header + length of body is off by one or two due to the extra newlines)
• comment_on_pr also adds some hidden content (<!-- … --> that includes the comment ID (--id), so that subsequent calls (from subsequent CI builds on the same PR) can know which comment to edit / delete. So that adds a bit to the length as well

Maybe the easiest solution is to simply reduce the value of github_comment_max_size in your code to something like 65400, to give some margin for those extras characters and id comment?