Automatically add GitHub PR review comment telling contributors how to sign ECA

Summary

Can the eclipsefdn/eca bot also add a comment to the PR when it fails telling contributors how to resolve the problem? At the moment the details link has some of that information, but you can't see that info without an account.

Steps to reproduce

Create a PR on Eclipse CDT without a valid ECA on file.

What is the current bug behavior?

This is what appears in, for example, https://github.com/eclipse-cdt/cdt/pull/357

but clicking on Details leads to:

What is the expected correct behavior?

An automatic comment that says something like:

Thank you for your contribution. Unfortunately the Eclipse Foundation ECA tool cannot find your signed ECA. Please complete the ECA at ....

Relevant logs and/or screenshots

(Add a link to or paste any relevant logs - please use code blocks (```) to format console output, logs, and code, as it's very hard to read otherwise.)

Priority

Urgent
High
Medium
Low

Severity

Blocker
Major
Normal
Low

Impact

This is a case where having some automation would help because:

The user will benefit because the feedback will be while they are currently looking at the issue, rather than waiting for a committer to get involved.
I have to do this on occasion, and I imagine this is repeated across all projects. I have had to do it at least 3 times in the last couple of months.
I like the idea of it looking like automatic bureaucracy that the bots enforce and that I don't have to get involved
I have rarely (if ever?) seen someone fail ECA check on GitHub and go correct it based on only the check failing.

Here is an example of what a user who was more engaged and asked questions: