feat: [CO 621] Allow LE certificates to be generated from Mailbox endpoint

[aheeva-yuliya]

What's changed:

• add async to remote execution
• start notifying global/domain recipients
• change certbot working dir bcz of updated certbot package
• slightly modify some old tests ("It ain't much, but it's honest work.") it won't help but better to run init server and clean data with every test

Current flow:

1. the admin requests to issue cert with api
2. mailbox starts checking everything what’s possible to check (if smth is wrong will thow an exeption)
3. if everything is ok will send a response
   The System is processing your certificate generation request. It will send the result to the Domain notification recipients.
4. meanwhile remote manager executing certbot command and recieve a message from it

we have 4 scenarios : №1 system failures (not related to certbot), №2 certbot failures, №3 certbot success (certificate recieved or certificate not yet due for renewal), №4 other (smth is wrong and wasn’t expected)

5. we notifying global about first 3 with the messages we got (not modifying them)
6. we notifying domain about №2 and about №3 (only if certificate was recieved) with the templates provided by Danielle Veri
7. №4 stored under opt/zextras/log/mailbox.log

Related PRs:
zextras/carbonio-core-utils#38
https://github.com/Zextras/carbonio-build/pull/50
https://bitbucket.org/zextras/carbonio-core/pull-requests/42

[frisonisland]

I think the whole map logic is a bit confusing. Maybe consider a more streamlined version where you just do, from the notify:

• parse output
• create global mime message
• create domain mime message
• send both messages using the same sender
  This way we avoid having if conditions in the same method to handle domain and global case.
  it is also easier to spot the wanted behavior.

[keshavbhatt]

I added some suggestions and requested some changes.

[Polpetta]

Some minor details to fix, the implementation seems ok!