feat(select): support []Builder type in Where method

[ch3nnn]

Extend the Where method in SelectStmt to accept a slice of Builder instances, allowing for multiple where conditions to be added conveniently in a single call.

[ch3nnn]

example:

func getWhere(req Request) (whereBuilder []dbr.Builder) {
	if req.ID > 0 {
		whereBuilder = append(whereBuilder, dbr.Eq("id", req.ID))
	}
	if req.Username != "" {
		whereBuilder = append(whereBuilder, dbr.Eq("username", req.Username))
	}

	return whereBuilder
}

func Example() {
	req := Request{ID: 1, Username: "xiaoming", Age: 18}
	Select("a", "b").From("table").Where(getWhere(req)).Load()
}

[ch3nnn]

help to review it. thank!
@taylorchu