Improve email service

[cofiem]

• Combine common operations into EmailService, including checking defaults.
• Allow additional email options to be templates.

[codecov]

Codecov Report

Attention: Patch coverage is 83.95062% with 13 lines in your changes missing coverage. Please review.

Project coverage is 52.60%. Comparing base (bb0787a) to head (edad820).
Report is 10 commits behind head on develop.

Files with missing lines	Patch %	Lines
typescript/api/services/EmailService.ts	80.00%	12 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2566      +/-   ##
===========================================
+ Coverage    52.52%   52.60%   +0.07%     
===========================================
  Files          179      167      -12     
  Lines         9376     8841     -535     
  Branches      1356     1280      -76     
===========================================
- Hits          4925     4651     -274     
+ Misses        4231     3968     -263     
- Partials       220      222       +2     

Flag	Coverage Δ
backend-bruno	44.53% <79.01%> (+0.58%)	⬆️
backend-mocha	49.30% <83.95%> (+0.61%)	⬆️
frontend-app-config	97.87% <ø> (ø)
frontend-core-lib	?
frontend-dashboard	74.53% <ø> (ø)
frontend-deleted-records	?
frontend-export	100.00% <ø> (ø)
frontend-local-auth	100.00% <ø> (ø)
frontend-manage-roles	63.33% <ø> (ø)
frontend-manage-users	59.81% <ø> (ø)
frontend-report	95.06% <ø> (ø)

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