SDK-1217 workaround tvOS SPM issue

[echo-branch]

Reference

SDK-1217 workaround tvOS SPM issue

Summary

Added preprocessor guards on all files that are not valid on tvOS. With other integration methods we can conditionally exclude these files, but it seems SPM does not allow this.

Motivation

Allow tvOS builds using SPM.

Type Of Change

• Bug fix (non-breaking change which fixes an issue)

Testing Instructions

Integrate Branch SDK into a tvOS app using SPM.
App should build properly.

cc @BranchMetrics/saas-sdk-devs for visibility.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 51.13%. Comparing base (4842da0) to head (8ff3e14).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1381      +/-   ##
==========================================
+ Coverage   51.03%   51.13%   +0.09%     
==========================================
  Files          66       66              
  Lines       10158    10158              
  Branches     3724     3724              
==========================================
+ Hits         5184     5194      +10     
+ Misses       4716     4705      -11     
- Partials      258      259       +1     

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[nsingh-branch]

Ran a test with a tvOS app with and without this change, looks good to me.