Annual review of dependencies

[regan-sarwas]

• Update to ArcGIS Runtime 100.11
• Use swift package manager for runtime
• Update to Xcode 12.5/Swift 5.4
• Resolve iOS 14 deprecation warnings

[regan-sarwas]

• Updated build instructions to use the swift package manager to install ArcGIS Runtime 100.12.0 with commits 31e6807 and f6e1f94.
• Removed iOS 14 deprecations with commit 886ff51
• Removed iOS15 deprecations with commit e0cd24d
• Tested build with Xcode 13, Swift 5.5 and SwiftUI 3, however there were no required changes to the code or build instructions.