Error while adding SPM support

[teendream]

I created Package.swift to the project. But there is issue with modules. Imports is not available to compiler. I created modulemap, indicated public headers path and project has umbrella header. I have errors while building package swift build.

Building for debugging...
/Users/cdti/Documents/Work/SocketRocket/SocketRocket/Internal/Proxy/SRProxyConnect.m:12:9: fatal error: 'NSRunLoop+SRWebSocket.h' file not found
#import "NSRunLoop+SRWebSocket.h"
^~~~~~~~~~~~~~~~~~~~~~~~~

Details:
https://stackoverflow.com/questions/78820826/error-while-building-spm-package-with-objc-code

Here are source codes:
https://github.com/teendream/SocketRocket/tree/feature/spm-support

[nastasiupta]

related #691