Use Downloadable API in FromBottleLoader.

[reitermarkus]

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Do we even need FromBottleLoader anymore? At least the from-URL part is useless since it doesn't work with OCI image URLs.

[Bo98]

Do we even need FromBottleLoader anymore?

brew install ./some.bottle.tar.gz is used. The URL variant shouldn't be however.

[reitermarkus]

Let's get rid of it then. I don't think we need to even deprecate it given it was broken before.

[MikeMcQuaid]

Thanks again @reitermarkus!