Improve code quality - ZH

[zhonghan721]

• Add logging
• Fix LoD violation in customer find
• Create model#clearFilteredCustomerList() and model#clearFilteredDeliveryList() for use in user logout
• Use model#showAllFilteredCustomerList()
• Fix missing space in error message for duplicate prefixes
• Remove unused User constructor

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (ff44e93) 84.02% compared to head (130ff3a) 84.45%.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #506      +/-   ##
============================================
+ Coverage     84.02%   84.45%   +0.43%     
- Complexity      984      993       +9     
============================================
  Files           121      121              
  Lines          2904     2934      +30     
  Branches        342      342              
============================================
+ Hits           2440     2478      +38     
+ Misses          397      389       -8     
  Partials         67       67              

Files	Coverage Δ
src/main/java/seedu/address/logic/Messages.java	91.66% <ø> (ø)
...ss/logic/commands/customer/CustomerAddCommand.java	100.00% <100.00%> (ø)
...s/logic/commands/customer/CustomerFindCommand.java	100.00% <100.00%> (ø)
.../address/logic/commands/user/UserLoginCommand.java	100.00% <100.00%> (ø)
...address/logic/commands/user/UserLogoutCommand.java	100.00% <100.00%> (ø)
...address/logic/commands/user/UserUpdateCommand.java	95.52% <100.00%> (+0.20%)	⬆️
...ogic/parser/customer/CustomerAddCommandParser.java	100.00% <100.00%> (ø)
...ress/logic/parser/user/UserLoginCommandParser.java	100.00% <100.00%> (ø)
...ess/logic/parser/user/UserUpdateCommandParser.java	95.45% <100.00%> (+0.33%)	⬆️
src/main/java/seedu/address/model/Model.java	100.00% <ø> (ø)
... and 3 more

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[juliusgambe]

LGTM

[juliusgambe]

Good one