Add support for sync_preferences webchannel command

[jonalmeida]

Moved from BZ-1968131.

We would like to add support on mobile for the SYNC_PREFERENCES command that exists for desktop - the accounts team plans to use this command to directly open the settings preferences after Sync signup is completed.

See: https://searchfox.org/mozilla-central/rev/e66fea62620cd4d77242764f9b09c91ae1040e1d/services/fxaccounts/FxAccountsWebChannel.sys.mjs#350-356

┆Issue is synchronized with this Jira Task

[data-sync-user]

➤ Andres Furlan commented:

Jonathan Almeida do you need support from iOS Team?

[jonalmeida]

This is something the iOS team should work on.

The Android side is already done, so iOS is the only platform left.

[jessilyndavis]

Heyo - is this still outstanding for iOS?

[lmarceau]

@jessilyndavis indeed, this wasn't picked up yet