Implement Generics API (#7424)

* Implement Generics API

* Add more generics tests

* Add more tests and Take method

* use delayed‑ops pipeline for generics API

* fix generics tests for mysql

* Support SubQuery for Generics

* Add clause.JoinTable helper method

* Fix golangci-lint error

* Complete the design and implementation of generic version Join

* improve generics version Joins support

* allow configuring select/omit columns for joins via subqueries

* finish generic version Preload

* handle error of generics Joins/Preload

* fix tests

* Add LimitPerRecord for generic version Preload

* fix tests for mysql 5.7

* test for nested generic version Join/Preload

* Add WithResult support for generics API

* test reuse generics db conditions

* fix data race

* remove ExampleLRU test

* Add default transaction timeout support

* fix test