Implement the ability for user-defined type casting

[Tigrov]

Related PRs

• Implement the ability for user-defined type casting db-sqlite#346
• Implement the ability for user-defined type casting db-mysql#385
• Implement the ability for user-defined type casting db-pgsql#395
• Implement the ability for user-defined type casting db-mssql#351
• Implement the ability for user-defined type casting db-oracle#314

Q	A
Is bugfix?	❌
New feature?	✔️
Breaks BC?	❌
Fixed issues	#892

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.23%. Comparing base (1811611) to head (b7fe597).

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #941   +/-   ##
=========================================
  Coverage     99.23%   99.23%           
- Complexity     1534     1540    +6     
=========================================
  Files            98       98           
  Lines          3804     3812    +8     
=========================================
+ Hits           3775     3783    +8     
  Misses           29       29           

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