Enable CloudWatch Sink through configuration file

[SubmittaBrian]

I'd love to be able to drop in this sink by adding it to app.config, but I don't think Serilog currently supports nested deserialization (or I haven't been able to make it work).

Would you consider adding an overload to AwsCloudWatchConfigurationExtension.AmazonCloudWatch that takes options and credentials as top-level parameters?

This would allow me to extend my prod app.config file like:

<appSettings>
    <!-- Log everything to Stackify for historical debug by DevOps-->
    <add key="serilog:using:Stackify" value="Serilog.Sinks.Stackify" />
    <add key="serilog:write-to:Stackify" />
    <add key="serilog:write-to:Stackify.restrictedToMinimumLevel" value="Debug" />

    <!-- Log Fatal errors to CloudWatch for real-time alert distribution e.g. pager duty systems -->
    <add key="serilog:using:AmazonCloudWatch" value="Serilog.Sinks.AwsCloudWatch" />
    <add key="serilog:write-to:AmazonCloudWatch"/>
    <add key="serilog:write-to:AmazonCloudWatch.logGroupName" value="myLogGroup/myEnvironment"/>
    <add key="serilog:write-to:AmazonCloudWatch.minimumLogEventLevel" value="Fatal"/>
    <add key="serilog:write-to:AmazonCloudWatch.awsRegion" value="us-west-1"/>
    <add key="serilog:write-to:AmazonCloudWatch.awsAccessKey" value="*****"/>
    <add key="serilog:write-to:AmazonCloudWatch.awsSecretKey" value="*****"/>
</appSettings>

[wparad]

Sounds like a good idea, feel free to make a PR.

[wparad]

For the record, I think the problem that the constructor requires parameters, we probably just need an empty constructor, and then we'll be good.