function to mask credit card numbers

[swanandapps]

What is needed:

Function to mask credit card numbers except for the last four digits.

Where to Code:

Find the Contribution Station in textMaskingAndSecurity.js.

Contribution Steps:

1. Create a development branch out of this issue. (Visible on the right column of the issue)
2. Code your function in that branch.
3. Raise a Pull Request to merge that branch into the main branch.

For more clarity, follow the visual guide in CONTRIBUTE.md.

[ssk090]

Hey @swanandapps, please checkout the implementation for the same here: #29