chore(swiftpm): Fix up CordovaLib Swift Package

[dpogue]

Platforms affected

iOS

Motivation and Context

When installing the package, Xcode complained about "extra" files (cordova.js, VERSION, and Info.plist) and also that we had both a include/Cordova.h file as well as a include/Cordova/ folder.

Description

• Moved the public framework Cordova.h header back into the Cordova/ folder where it was previously, so that it won't get detected by Swift Package Manager.
• Added a list of excluded files to Package.swift so it won't complain about extraneous files

Testing

• All unit tests pass
• Added CordovaLib to a new ObjectiveC project using Swift Package Manager with no errors

Checklist

• I've run the tests to see all new and existing tests pass

[codecov-commenter]

Codecov Report

Merging #1160 (92774ea) into master (f12abcc) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1160   +/-   ##
=======================================
  Coverage   74.86%   74.86%           
=======================================
  Files          13       13           
  Lines        1723     1723           
=======================================
  Hits         1290     1290           
  Misses        433      433           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update f12abcc...92774ea. Read the comment docs.

[erisu]

LGTM