Add events before and after handling bulk imports

[hyzx86]

Scene:

1. Process the data before bulk import
2. Batch update dynamic SQL indexes after batch import

I am using FreeSql as an ORM tool that supports dictionary type data insertion/update (including batch mode) http://www.freesql.net/en/guide/insert-or-update.html#_2-ifreesql-insertorupdatedict

var dic = new Dictionary<string, object>();
dic.Add("id", 1);
dic.Add("name", "xxxx");

fsql.InsertOrUpdateDict(dic).AsTable("table1").WherePrimary("id").ExecuteAffrows();

related: https://github.com/OrchardCMS/OrchardCore/issues/8869