[NEW] Add ability to disable email notifications globally

[ferdifly]

@RocketChat/core

Closes #3211

I might add the option to hide message content later on but I think this will do as a first PR.

Please let me know how I can improve this PR (by adding some tests maybe?).

Screenshots:

[geekgonecrazy]

Thanks for the contribution! Left a comment in line :)

[howq]

@ferdifly hi,when I find the issue of disabling email notification globally.I'm so glad.But I can't find in the 0.64.0 tag.Why this useful rp was not accepted.

[ferdifly]

@howq Apparently my commit keeps all e-mails from being sent (see #3211 (comment)). Thanks for reminding me of this, I somehow lost track of this commit due to other stuff going on. I'll try to take a look at it later this week.

[Irker]

up?

[javiergoni]

Any update of this?

[ferdifly]

Since interest still seems high on this feature I took a look at my branch again.

According to my understanding of the code and terminal output, password recovery mails are still being sent when email notifications are disabled #3211 (comment).

Maybe someone from @RocketChat/core could consider this PR again and let me know what there is left to do. Did my commit 23e0195 address @geekgonecrazy change request correctly?

addressed

[ferdifly]

@geekgonecrazy I've addressed your change request and merged the latest develop branch. However ci/circleci: build-and-test/hold is stuck pending and I'm unsure whats causing it.

[geekgonecrazy]

That's fine and normal.

@rocketchat/core this seems like a great change to add. I know I personally have needed something like this a few times for disabling email sending.