ZIP Filesystem backed resource loader

Add a NIO.2 FileSystem-backed resource loader implementation.

Note that right now we have:

• PathResourceLoader - this is the bulk of the NIO.2 implementation, which provides basic handling for filesystem access, manifest parsing, etc.
• FileResourceLoader - based on PathResourceLoader, this class adds functionality to locate and use (and optionally write) an index file.
• The new zip-based provider proposed by tomazcerar - based on PathResourceLoader, this class adds a mount-zip-FS step.

The new resource loader implementation should be a generic extension to PathResourceLoader which adds support for registering and closing a FileSystem.

The initialization block of ResourceLoaders should use the FileSystemProvider.installedProviders() method to determine if the zip filesystem provider is present. The default implementation of ResourceLoaders.createJarResourceLoader() should use the new file system backed resource loader by default if the provider is found. The provider's FileSystemProvider.newFileSystem(URI,Map) can then be used directly to create the backing file systems on demand, to pass to the file system resource loader.

Part 2 will be to solve code signing.