Fix #6279: Rust fxa Staging server support

[garvankeeley]

No description provided.

[mozillamobilebot]

SwiftLint found issues

Warnings

File	Line	Reason
DevicePickerViewController.swift	144	Force casts should be avoided. (force_cast)
DevicePickerViewController.swift	146	Force casts should be avoided. (force_cast)
DevicePickerViewController.swift	158	Force casts should be avoided. (force_cast)
AppDelegate.swift	45	Prefer empty collection over optional collection. (discouraged_optional_collection)
AppDelegate.swift	50	Prefer empty collection over optional collection. (discouraged_optional_collection)
AppDelegate.swift	84	Prefer empty collection over optional collection. (discouraged_optional_collection)
AppDelegate.swift	195	Prefer empty collection over optional collection. (discouraged_optional_collection)
AppDelegate.swift	491	Prefer empty collection over optional collection. (discouraged_optional_collection)
AppDelegate.swift	400	Don't add a space between the method name and the parentheses. (no_space_in_method_call)
AppDelegate.swift	399	Variables should not have redundant type annotation (redundant_type_annotation)
AppDelegate.swift	23	Limit vertical whitespace to a single empty line. Currently 2. (vertical_whitespace)
RustFirefoxAccounts.swift	1	Header comments should be consistent with project patterns. (file_header)
RustFirefoxAccounts.swift	97	Force casts should be avoided. (force_cast)
Profile.swift	1098	Prefer empty collection over optional collection. (discouraged_optional_collection)
Profile.swift	431	Force tries should be avoided. (force_try)
Profile.swift	506	Force tries should be avoided. (force_try)
Profile.swift	808	Fallthroughs can only be used if the case contains at least one other statement. (no_fallthrough_only)
Profile.swift	905	Prefer _ = foo() over let _ = foo() when discarding a result from a function. (redundant_discardable_let)

Errors

File	Line	Reason
DevicePickerViewController.swift	67	There should be no space before and one after any comma. (comma)

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[isabelrios]

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