The UTF8 format of the Windows system has BOM.
We add a new user property to `Outfile/Export`。Therefore, when exporting Doris data, users can choose whether to bring BOM on the beginning of the CSV file.
**Usage:**
```sql
-- outfile:
select * from demo.student
into outfile "file:///xxx/export/exp_"
format as csv
properties(
"column_separator" = ",",
"with_bom" = "true"
);
-- Export:
EXPORT TABLE student TO "file:///xx/tmpdata/export/exp_"
PROPERTIES(
"format" = "csv",
"with_bom" = "true"
);
```
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