fix(addBuildPhase): adding of PBXBuildFile entries to lookup table

[erisu]

• Add PBXBuildFile entry to filePathToBuildFile lookup table when a valid identifier is present.
• Valid identifier is determined when the fileReference has either a path or name property value.
• The path property takes priority when both path and name are defined.
• When the path and name properties are not defined the entry is not added to the lookup table.

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Additionally, this PR

• Added some in-code documentation.
• Using JSDocs
• Added a basic example

Any additional JSDoc changes I would like to keep under #171. This PR only added the minimum required to document addBuildPhase.

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The main purpose of this PR is to resolve and close PR #140.

Closes #140

PR #140 was attempting to resolve a failure that occurred when looping through build files to create the filePathToBuildFile lookup table, where a file reference did not have path defined. The PR attempted to resolve this by skipping when the path property of the file reference was missing.

There are cases where name can be used instead of path. In those cases, name appears to serve as the file path, with path resolution determined by the file reference's sourceTree. But generally, name often matches the file name.

Same issue was reported here: apache/cordova-ios#1357

This PR takes a different approach and check if either path or name is defined before it skipped the build file.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.34%. Comparing base (04fc2dd) to head (1a38327).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #174      +/-   ##
==========================================
+ Coverage   97.31%   97.34%   +0.02%     
==========================================
  Files          51       51              
  Lines       10968    11058      +90     
==========================================
+ Hits        10674    10764      +90     
  Misses        294      294              

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