Add Storage Info Providers

[yauhenipakala]

Description

Get info about available storage space.

API Changes

Added:

XToolkit.Common:

• IStorageInfoProvider
• StorageInfo
• StorageType

XToolkit.Common.iOS:

• IosStorageInfoProvider

XToolkit.Common.Droid:

• DroidStorageInfoProvider

XToolkit.WhiteLabel.Droid:

• ModernDroidStorageInfoProvider

Platforms Affected

• Core (all platforms)
• iOS
• Android

Behavioral/Visual Changes

None

Before/After Screenshots

Not applicable

PR Checklist

• [x] I have read the CONTRIBUTING document
• [x] My code follows the code styles
• [x] Targets the correct branch
• [x] Tests are passing (or failures are unrelated)