2.0.0 (SPM)

• Swift Package Manager support exposes public headers and restructures code for SPM format.
• Renamed framework from crs-ios to CoordinateReferenceSystems in SPM (dashes break SPM bundle resources)
• Updated to use NS_ENUM for C enum for Swift/Objective-C interoperability
• Updated tests (Objective-C based and Swift based tests)
• Removed Cocoapods (deprecated)
• Updated build instructions and github workflows
• Full Changelog: 1.0.5...2.0.0