Implementing privacy API

[dmitriim]

Moodle plugins need to implement privacy API https://docs.moodle.org/dev/Privacy_API otherwise unit tests will fail.

[valentineus]

Thanks! It's a valuable issue. I didn't know about that.

I have got a little mess in the repository.
Can you set PR to v3.0.0-stable brach?

[dmitriim]

Hi @valentineus! Not really relevant, to this issue, but is there any reason why v3.0.0-stable requires moodle 3.8 and not 3.7 as minimum version? https://github.com/valentineus/moodle-webhooks/blob/v3.0.0-stable/version.php#L30
As far as I can see it doesn't use anything specific to 3.8. Will it possible to set 3.7 as a minimum required version?
In our particular case we use this plugin in 3.7 and would like to have the latest stable code. We have to fork v3.0.0-stable, change the required and then spend extra effort to support our forked branch.

I you are ok with that chnage, for your convenience I have created #19

[dmitriim]

Created #18 as requested

[valentineus]

Thank you, Dmitrii! Your pull requests are excellent. I released version v3.0.5 (2020051600).