implement conversion from and to binary strings for mssql types

[lovasoa]

This is the same as #2546 , but for binary strings instead of datetimes.

Currently, Encode<'_, sqlx::Any> is not implemented in sqlx for Vec<u8>. It is implemented fro sqlite, postgres and mysql, but not for mssql.

Would you be open to a pull request implementing it ?

I'd need it to add support for microsoft sql server in SQLPage (sqlpage/SQLPage#2)

[lovasoa]

I implemented that in https://github.com/lovasoa/sqlx