Extract getNodeText and add Unit Tests

[jeryj]

We needed to get an accessibility fix in to resolve (#47767) before the release. Given it was such a short timeline, having the fix be beta tested more was more important than this refactor. As a follow-up, there's some refactoring we could do to improve the getNodeText implementation from #54902

1. Extract it to its own file
2. Add unit tests to verify the correct functionality
3. Refactor it to remove code that won't be run.

[alexstine]

#54902 (comment)

[sreeragdas]

@alexstine , i am interested in working , can u pls share me the details

[alexstine]

@sreeragdas All details are in the description above. Essentially, we need to move that helper function to a new file and write unit tests around it to prevent regressions. Thanks.

[oceantober]

Hello! My team of 3 beginner students from Code Day would like to work on this issue!

[alexstine]

@oceantober Sure, have them open a PR. Happy to review their work. Thanks.