Allow replacing ConfigurationManager for reading values

[javvids]

CoreMemoryCache uses ConfigurationManager for reading values. This doesn't work in Azure Functions V2. Can we have a custom option of providing cache values?

[fredericDelaporte]

Something like nhibernate/nhibernate-core#2116?

[fredericDelaporte]

By the way, configuration can be programmatically done, in case you have not seen.
CoreMemoryCacheProvider exposes some static members for this. Most cache providers do the same.

[javvids]

Thanks