Migrating 'Text Area' component

**path to the component**

- /src/atoms/TextArea.js

**DoD**

- convert the file to .ts extension
- define an interface for props in the component
- define an interface for internally used states (if any)
- define types for variables (if any)

Contribution steps can be found - [https://github.com/99xt/first-born/wiki/Migrating-to-TypeScript](https://github.com/99xt/first-born/wiki/Migrating-to-TypeScript)

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Open /src/atoms/TextArea.js and read the linked migration guide first. Convert the file to TypeScript, adding interfaces for props and any internal state and types for variables where needed. Done means the component is saved with a .ts extension and all listed typing requirements are met.

Written by the indexing model from the issue text.