feat: separate tagged image providers

[kzantow]

This PR makes the following top-level changes:

• image.Provider interface has been reworked so providers have Name() method
• image.Provider.Provide is required to return an image object fully populated (e.g. .Read() has been called)
• A top-level stereoscope.ImageProviders function is added, allowing interested parties (e.g. syft) to get access to the individual tagged image providers
• A top-level stereoscope.ImageProviderConfig is added which is the uber-configuration needed by all stereoscope-defined providers

Note: the top-level GetImage and GetImageFromSource remain unchanged with the caveat that the image.Source has changed from an int to a string. These functions will use the default set of image providers, so should continue to behave about the same as before, with the other caveat that if the user has a docker daemon and another supported daemon (containerd, podman), each daemon may be tried instead of stopping after attempting docker, which is the behavior today.

TODO:

• should image.Provider have a Tags() []string method and ImageProviders(...) returns []image.Provider? (no, this is now []collections.TaggedValue[image.Provider])
• fix existing tests
• add more tests exercising the full functionality of each image provider
• fully integrate with syft PR Refactor source creation and add --from flag syft#2610

[wagoodman]

should image.Platform be a parameter to the Provide function instead of configuration?

yeah, I think so

[wagoodman]

naming: is Resolver better than Provider (or something else)?

I'm a fan of "provider" here, but will give it some thoughts