storage: add token-based upload for hosting

[guaraqe]

From @arthyn: This fixes LAND-999 by adding new state to the %storage backend and allows hosting users to customize whether they want to use Tlon provided presigned URLs or their own custom credentials for direct S3 uploads.

Similar changes are being pulled into the Tlon app here: tloncorp/tlon-apps#2906

[jamesacklin]

@guaraqe Thanks, looking good so far. A note: Tlon S3 hosting should only be available to Tlon Hosting customers. Anyone else should get the S3 endpoint form they see now.

[linear]

LAND-999 s3: UI for enabling/disabling Tlon Hosting s3 for hosted ships

Related: HOST-69, specifically this comment: HOST-69

In order to support s3 we're going create secrets urbit side that then can be provided to hosting.

nathan is working on that requirement in LAND-1000

We will also need a way for users to enable/disable Tlon Hosting s3.

The requirements:

• We can use the remote storage settings in landscape
• All of this appears only for Tlon Hosted ships
• If the user has s3 already configured then by default have Tlon Hosting s3 disabled
• If the user does not have s3 already configured then have it default enabled
• When enabled - it does not overwrite any custom config, but separately turns on hardcoded defaults provided by hosting
• If a user with custom s3 config attempts to enable Tlon Hosting s3, keep their custom config in the custom config settings, but enable Tlon Hosting s3. Also explain to the user what is happening. If the user then disables Tlon Hosting s3, revert back to their existing custom config.
• When the Tlon Hosting config is enabled, this config should use a hardcoded URL provided by hosting.
• james is working on designs for some of this, assigning to him now for handling.

Basically most users should just wake up with an OTA that gives them out of the box s3 and they'll never need to know about this settings existence. We will also handle the couple of other corner cases.

[midsum-salrux]

Everything re: getting and using the genuine token looks good to me.

[patosullivan]

Lgtm!