Add IStorageProvider implementation based on IFileProvider

[ronaldbarendse]

This PR builds upon #11 (comment).

Instead of wrapping the media IFileSystem (Umbraco's read/write IO abstraction) as an IFileProvider (ASP.NET Core read-only IO abstraction) to then use in the StaticFileMiddleware, this directly implements the IFileProvider for the read-only part and exposes the write-operations in a new IStorageProvider abstraction.

This is a POC and still needs a lot of work!

[ronaldbarendse]

These are just some idea's that came up recently related to reworking the file providers:

• Add support for getting (generating/storing) and validating file hashes: this can be used when comparing files, e.g. as part of a deployment and in the case of Azure Blob Storage the MD5 hash can already be retrieved from the blob properties;
• Instead of getting a boolean result from the move/copy/delete actions, return more context (e.g. to differentiate between a failed move, because a non-overwriting and non-recursive move found either subdirectories in the source or an existing file in the destination). This could be done using result enums, by throwing a custom exception (and possibly implement Try* methods) or something similar/identical to the CMS Attempt/OperationResult;
• Add async versions of the IFileProvider methods: GetDirectoryContents and GetFileInfo;
• Create a base wrapper implementation that accepts an existing IFileProvider, so we can e.g. make PhysicalStorageProvider inherit from the StorageProviderBase class and accept a PhysicalFileProvider (instead of having to inherit from this class).

[EelmanE]

Any chance this will continued? It seems related with an performance issue several users are experiencing in different versions of Umbraco (including 15).

[henrikbn]

Any chance this will continued? It seems related with an performance issue several users are experiencing in different versions of Umbraco (including 15).

Just bumping this again as it is still a very big issue for anyone using Azure Blob Storage (Or S3 storage). The media section is very slow and for us often crashes the site when an editor goes there...

We have added the temporary fix as mentioned, but would be nice with a more permanent fix.