No async overload for SqlConnection.Open with SqlConnectionOverrides

[ajcvickers]

I'm currently working on consuming the new Open(SqlConnectionOverrides overrides) method in EF Core. However, there is no OpenAsync equivalent.

See #29 and dotnet/efcore#7283

[cheenamalhotra]

Hi @ajcvickers

We noticed that the delay of 10 seconds due to transient fault handling did not apply to OpenAsync(), hence this option was not introduced to OpenAsync() Ref #463 (comment)

[ajcvickers]

@cheenamalhotra Missed that--sounds good.