[Feature] Email Manager

[titouanmathis]

This PR adds a new EmailManager which can be used to configure a custom SMTP server for sending mail with the wp_mail() function as well as logging success and failures when sending mails.

To-do

• Add PHPMailer configuration tests
• Add logger tests

[codecov]

Codecov Report

Attention: Patch coverage is 55.55556% with 12 lines in your changes are missing coverage. Please review.

Project coverage is 66.87%. Comparing base (0302eaf) to head (3b9a704).

Files	Patch %	Lines
src/Managers/EmailManager.php	55.55%	12 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop      #22      +/-   ##
=============================================
- Coverage      67.53%   66.87%   -0.67%     
- Complexity       168      179      +11     
=============================================
  Files             11       12       +1     
  Lines            462      489      +27     
=============================================
+ Hits             312      327      +15     
- Misses           150      162      +12     

Flag	Coverage Δ
unittests	66.87% <55.55%> (-0.67%)	⬇️

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