Implement the ability for user-defined type casting

[Tigrov]

Related PR

• https://github.com/yiisoft/db/pull/941

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

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 97.96%. Comparing base (1af51f9) to head (ba6ce71). Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #314   +/-   ##
=========================================
  Coverage     97.96%   97.96%           
  Complexity      220      220           
=========================================
  Files            23       23           
  Lines           738      738           
=========================================
  Hits            723      723           
  Misses           15       15           

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