Move SQL specifics to builder.

internal/sqladapter/testing/adapter.go.tpl

internal/sqladapter/testing/adapter_benchmark.go.tpl

internal/sqladapter/tx.go

mysql/database.go

mysql/mysql.go

mysql/template_test.go

mysql/tx.go

postgresql/database.go

postgresql/postgresql.go

postgresql/template_test.go

postgresql/tx.go

ql/database.go

ql/ql.go

ql/template_test.go

ql/tx.go

sqlbuilder/builder.go

sqlbuilder/builder_test.go

sqlbuilder/wrapper.go

sqlite/database.go

sqlite/sqlite.go