Add persistent settings and preferences capability to Web driver

[Bluebugs]

Is your feature request related to a problem? Please describe:

The web driver in work does not currently have the ability to remember settings between run. It would be nice to have this feature working also in the web.

Is it possible to construct a solution with the existing API?

This will enable the settings API to be supported on the web, no new API should be necessary.

Describe the solution you'd like to see:

I think that the web local storage API should work for this use:

https://developer.mozilla.org/en-US/docs/Web/API/Web_Storage_API

[andydotxyz]

We need to ensure this applies to a fully operational preferences API too

[andydotxyz]

$500 is currently allocated for eligible contributors completing this work (see Contributing: Membership).

Completed work will mean full storage and preferences work using local storage.

[dweymouth]

Does settings storage need to apply to all Fyne web apps? If so, that will probably need to use cookies instead of local storage, as local storage is per-origin.

[andydotxyz]

Ah, this was written up as a little ambiguous. As I see it the important settings are communicated to the browser and we will use those internally. So the outstanding ticket is really:

• Add support for storage APIs (file persistence etc)
• Preference storage (for apps to store data that will be picked up next load)

I don't think any of this should be communicated out to other apps - so no cookies needed.

[dweymouth]

Ah, I think storage APIs should be a separate ticket. Fyne settings and app preferences can both use local storage (as long as we're OK with saved Fyne settings applying per-webapp instead of system-wide like desktop and mobile).

The storage API (ie general file persistence) has to use something else since local storage is limited to 10 MiB per app I think. And I guess each one should have half the original bounty? ;)

[andydotxyz]

You may have a point there. Happy to split the bounty as you suggest

[andydotxyz]

As discussed, this ticket is now $250 bounty, split with #4634

[kkoreilly]

I have the package https://github.com/cogentcore/core/tree/main/system/driver/web/jsfs, which I use in Cogent Core on the web platform to implement persistent settings and a full, Go stdlib compatible file system capable of storing any data using Indexed DB. You are free to adopt this code to fyne, or I can move it into a separate repository if you want to import it.

[dweymouth]

Fixed on develop