Spm support

[MosheBerman]

This PR defines a Swift package for KosherCocoa.

Additional changes

Project Configuration Updates:

• Updated objectVersion from 46 to 70 to align with the latest Xcode project format.

File Reference Updates:

• Removed outdated file references for KosherCocoa.h, KCAstronomicalCalendar+DateManipulation.h, and KCAstronomicalCalendar+DateManipulation.m and replaced them with new references. [1] [2]
• Removed references to test files and resources that are no longer needed. [1] [2]

Group and Section Reorganization:

• Reorganized project groups to better reflect the project's structure, renaming groups such as KosherCocoa to Sources and KosherCocoaTests to Tests. [1] [2]
• Introduced PBXFileSystemSynchronizedBuildFileExceptionSet and PBXFileSystemSynchronizedRootGroup sections to manage file synchronization exceptions and root groups. [1] [2]

Build Configuration Adjustments:

• Updated Swift compilation settings to use wholemodule compilation mode and adjusted optimization levels for the release configuration.