Rearrange expression namespaces

[Tigrov]

Q	A
Is bugfix?	❌
New feature?	❌
Breaks BC?	✔️
Fixed issues

Related PR

• Rearrange expression namespaces db#1052

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.75%. Comparing base (4342950) to head (fd28f74).

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #365   +/-   ##
=========================================
  Coverage     97.75%   97.75%           
  Complexity      241      241           
=========================================
  Files            26       26           
  Lines           800      800           
=========================================
  Hits            782      782           
  Misses           18       18           

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