fix(TypeHandler): use the custom type handler when packing a list parameter

[tlecomte]

Fixes #2067

The code for SqlMapper.PackListParameters was not using the custom type handler. This caused an error like No mapping exists from object type xxxxx to a known managed provider native type. when passing a collection parameter to a query, when the type of the collection items is not natively supported by the SQL client, and when a custom TypeHandler is registered for it.

Here this is fixed by using the same logic that is already in DynamicParameters.AddParameter.

A unit test is added to cover the scenario.

[tlecomte]

Dear @mgravell, please see here a PR to fix an issue with list parameters and custom type handlers. Thank you very much for considering this!

[SimonAfek]

I was just about to post an issue regarding this very thing when I saw this pull request. Hope this gets merged soon.

I have a custom type handler for Guids that get stored as binary(16) in my database. Works fine for single parameters in queries like SELECT * FROM [TableName] WHERE [Id] = @Id, but when I supply a list parameter for a query like SELECT * FROM [TableName] WHERE [Id] IN @Ids;, Dapper reverts back to treating them with the default handler instead.

[aquamoth]

A year later, and we have the exact same issue @SimonAfek is describing.
What prevents this from being merged? If it is a quality issue, I am sure we can pitch in to resolve outstanding issues.