Enables nested spice stores to be inlined in separate sections

[simonbs]

Adds support grouping settings into sections.

Description

Settings can be grouped into sections by providing the .inline presentation style when nesting a spice store.

final class AppSpiceStore: SpiceStore {
    @Spice(requiresRestart: true) var environment: ServiceEnvironment = .production
    @Spice(name: "API URL") var apiURL = "http://example.com"
    @Spice(presentation: .inline) var debugging = DebuggingSpiceStore()
}

final class DebuggingSpiceStore: SpiceStore {
    @Spice var enableLogging = false
    @Spice var clearCache = {
        try await Task.sleep(for: .seconds(1))
        URLCache.shared.removeAllCachedResponses()
    }

    fileprivate init() {}
}

Similarly, a nested spice store can be presented modally with the .modal presentation style.

@Spice(presentation: .modal) var debugging = DebuggingSpiceStore()

Motivation and Context

Grouping settings into sections improves organization and enhances readability.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)