Cursor position in FormattedInput

[priyang12]

Fixes #1248

Technical details
Corrected Cursor Position using Diff package by creating a function.

Screenshots

Screen.Recording.2022-03-31.at.7.30.11.PM.mov

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[codecov-commenter]

Codecov Report

Merging #1257 (f65f6b8) into master (950724c) will not change coverage.
The diff coverage is n/a.

❗ Current head f65f6b8 differs from pull request most recent head 1771d29. Consider uploading reports for the commit 1771d29 to get more accurate results

@@           Coverage Diff           @@
##           master    #1257   +/-   ##
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  Coverage   93.46%   93.46%           
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  Files         114      114           
  Lines        4404     4404           
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  Hits         4116     4116           
  Misses        288      288           

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[pavish]

@priyang12 Good job on this PR!

There is an edge case I noticed, when you edit a lengthy number (in the middle) which has a repeated number in it, eg.,100000000, the cursor position is not placed accurately.

However, before handling this, I am re-thinking the whole input. Here's the relevant discussion: #1268.

I'm placing the review and merge on hold until that discussion is resolved by the core team.

[priyang12]

@pavish ok thanks for the update.

[pavish]

The discussion #1268 is resolved.

@seancolsen I'm assigning you as the reviewer for this PR, since you've been the one working on the NumberInput component.

[seancolsen]

@priyang12 Thanks again for this PR.

For the most part, your work has improved the behavior of the input, so I'm merging this PR. However, as @pavish mentioned, there are some additional edge cases that we'll still need to handle. To track the work of handling those additional edge cases, I've opened #1284.

I pushed a commit to this PR which restructures your code as follows:

• I renamed the function setCursorToPostion to getCursorPositionAfterReformat. That fixes the spelling error in "position" and makes the name more specific.
• I made the function into a pure function and moved it to a utils file so that it's easier to test with unit tests.
• I changed the argument structure to use named arguments with names that pertain to the purpose of the function instead of the purpose of the component. This increases readability when calling the function and reduces the risk of calling the function with the arguments mixed up.
• I removed the TypeScript type any from within the function. We don't need to use it here. We should only use any as a last resort.
• I made some other small naming changes within the function to increase readability.
• I wrote a unit test with several test cases that pass. And I added more test cases that fail (with those test cases commented out.)
• I removed the logic which checks to see if the last character is a number. We shouldn't need to do that. The process of setting the cursor position should work regardless of the characters in the text. One important reason is that the FormattedInput component is a general purpose component which serves as a building block for other components. So far, we only have NumberInput. But we may someday have others, like PhoneNumberInput or DateInput or CreditCardNumberInput. Further, within NumberInput specifically, sometimes the last character of the number isn't a digit. For example, we need to gracefully deal with an input of 12..