Add a static callback variable to HttpUtil for certificate verification

[Wyllyam73]

What is the current behavior?

When making connections to from AWS lambdas to snowflake servers, SSL is being rejected because of certificate name issue. We cannot fix the certificate but we know we can trust the specific certificate based on internal rules. For .NET 4.5, we used to add a custom callback on ServicePointManagerHelper so we can examine each certificate and selectively approve as needed based on specific criteria for both the host, certificate, and certificate chain. For .net core, the language removed this feature.

Currently, we are receiving this error based on how the certificate is being processed at the system level.
"The remote certificate is invalid according to the validation procedure: RemoteCertificateNameMismatch".

What is the desired behavior?

The callback function would be applied to the returned HttpMessageHandler within the HttpUtil.setupCustomHttpHandler function.

How would this improve snowflake-connector-net?

Provide users of the library with more control over certificate verification in obscure scenarios where certificate control is not possible from the server side and provide a consistent method across .net libraries for certificate analysis/processing via custom activities.

References, Other Background

What is your Snowflake account identifier, if any?