Support fields for cache retrieval

[pergerch]

Instead of only looking for a property that implements IMemoryCache / IDistributedCache we shall also allow fields.

In case both a property and a field of type IMemoryCache / IDistributedCache is found in the class, the property will implicitly take precedence.

Code sample:

[Cache]
public class BasicSample
{
 public BasicSample(IMemoryCache memoryCache)
 {
 MemoryCache = memoryCache;
 }

 protected IMemoryCache MemoryCache;

 // ...
}