Add an option to enable setting a different CacheRoot

Author: stefannikolei

src/ImageSharp.Web/Caching/PhysicalFileSystemCache.cs

@@ -72,7 +72,10 @@ public PhysicalFileSystemCache(
 
             // Allow configuration of the cache without having to register everything.
             this.cacheOptions = cacheOptions != null ? cacheOptions.Value : new PhysicalFileSystemCacheOptions();
-            this.cacheRootPath = Path.Combine(environment.WebRootPath, this.cacheOptions.CacheFolder);
+            var cacheRoot = string.IsNullOrEmpty(this.cacheOptions.CacheRoot)
+                ? environment.WebRootPath
+                : this.cacheOptions.CacheRoot;
+            this.cacheRootPath = Path.Combine(cacheRoot, this.cacheOptions.CacheFolder);
             if (!Directory.Exists(this.cacheRootPath))
             {
                 Directory.CreateDirectory(this.cacheRootPath);

src/ImageSharp.Web/Caching/PhysicalFileSystemCacheOptions.cs

@@ -12,5 +12,10 @@ public class PhysicalFileSystemCacheOptions
         /// Gets or sets the cache folder name.
         /// </summary>
         public string CacheFolder { get; set; } = "is-cache";
+
+        /// <summary>
+        /// Gets or sets the cache root folder.
+        /// </summary>
+        public string CacheRoot { get; set; }
     }
 }