MySqlBulkCopy should have a BatchSize setting

[rferraton]

Is your feature request related to a problem? Please describe.
I saw that the MySqlBulkCopy (which is great) use a const 1MB to read from IDataReader and write to target. I think it could lead to many IOs and disk stress on high load (parallel). I saw that before chunking with 1MB there was issue with network paquet size

Describe the solution you'd like
I suggest to add the possibility to change this value (1MB) using a class setting BatchSize or BatchLen that would have a 1MB default value
I found the const 1MB here :

MySqlConnector/src/MySqlConnector/MySqlBulkCopy.cs

Line 381 in bbdbd78

const int maxLength = 1048575;

Describe alternatives you've considered

Additional context

[bgrainger]

This limitation was introduced by feea06b to fix #780.

MySQL Server 8.0 increased the default value of max_allowed_packet to 64MiB (up from 4MiB in 5.7) so this constant may be much too conservative for current servers.

A larger default size with a mechanism (such as a class property) to opt out could be a good solution.