feat: Notifications mailing system

[orronai]

• Added mailing system every 2 hours for notifications
• Added subscription option for every user
• Added celery task for sending mails
• Added translations for babel

[codecov[bot]]

Codecov Report

Merging #327 (859742e) into master (6f13160) will increase coverage by 0.20%. The diff coverage is 90.62%.

:exclamation: Current head 859742e differs from pull request most recent head 48d4811. Consider uploading reports for the commit 48d4811 to get more accurate results

@@            Coverage Diff             @@
##           master     #327      +/-   ##
==========================================
+ Coverage   84.08%   84.28%   +0.20%     
==========================================
  Files          63       66       +3     
  Lines        2946     3035      +89     
==========================================
+ Hits         2477     2558      +81     
- Misses        469      477       +8     

Impacted Files	Coverage Δ
lms/lmsdb/bootstrap.py	15.96% <20.00%> (+0.17%)	:arrow_up:
lms/utils/mail.py	98.27% <96.29%> (+1.05%)	:arrow_up:
lms/lmsdb/models.py	91.33% <100.00%> (+0.25%)	:arrow_up:
lms/lmsweb/__init__.py	97.82% <100.00%> (+0.15%)	:arrow_up:
lms/lmsweb/views.py	93.27% <100.00%> (+0.15%)	:arrow_up:
lms/models/notifications.py	90.00% <100.00%> (+0.71%)	:arrow_up:
lms/models/users.py	94.28% <100.00%> (+1.69%)	:arrow_up:
lms/utils/__init__.py	100.00% <100.00%> (ø)
lms/utils/config/__init__.py	100.00% <100.00%> (ø)
lms/utils/config/celery.py	100.00% <100.00%> (ø)

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[sourcery-ai[bot]]

Sourcery Code Quality Report

✅  Merging this PR will increase code quality in the affected files by 0.32%.

Quality metrics	Before	After	Change
Complexity	1.81 ⭐	1.77 ⭐	-0.04 👍
Method Length	37.28 ⭐	37.21 ⭐	-0.07 👍
Working memory	6.70 🙂	6.64 🙂	-0.06 👍
Quality	80.66% ⭐	80.98% ⭐	0.32% 👍

Other metrics	Before	After	Change
Lines	2550	2698	148

Changed files	Quality Before	Quality After	Quality Change
lms/lmsdb/bootstrap.py	79.77% ⭐	80.37% ⭐	0.60% 👍
lms/lmsdb/models.py	84.48% ⭐	84.68% ⭐	0.20% 👍
lms/lmsweb/init.py	64.84% 🙂	62.45% 🙂	-2.39% 👎
lms/lmsweb/views.py	75.31% ⭐	75.47% ⭐	0.16% 👍
lms/models/notifications.py	86.95% ⭐	85.84% ⭐	-1.11% 👎
lms/models/users.py	89.57% ⭐	88.61% ⭐	-0.96% 👎
lms/utils/init.py	%	99.83% ⭐	%
lms/utils/mail.py	85.34% ⭐	85.30% ⭐	-0.04% 👎
tests/conftest.py	90.98% ⭐	91.07% ⭐	0.09% 👍
tests/test_notifications.py	70.46% 🙂	73.00% 🙂	2.54% 👍

Here are some functions in these files that still need a tune-up:

File	Function	Complexity	Length	Working Memory	Quality	Recommendation
lms/lmsweb/views.py	comment	13 🙂	202 😞	8 🙂	50.15% 🙂	Try splitting into smaller methods
tests/test_notifications.py	TestNotification.test_user_commented_after_check	0 ⭐	215 ⛔	12 😞	53.71% 🙂	Try splitting into smaller methods. Extract out complex expressions
lms/lmsweb/views.py	view	8 ⭐	140 😞	10 😞	56.16% 🙂	Try splitting into smaller methods. Extract out complex expressions
lms/lmsweb/views.py	login	5 ⭐	129 😞	12 😞	56.69% 🙂	Try splitting into smaller methods. Extract out complex expressions
lms/lmsdb/models.py	Solution._base_next_unchecked	0 ⭐	95 🙂	20 ⛔	57.42% 🙂	Extract out complex expressions

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• 🙂 good
• 😞 poor
• ⛔ very poor

The 👍 and 👎 indicate whether the quality has improved or gotten worse with this pull request.

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