Add Feature to Copy and Paste .env File Environment in AWS Amplify

### Before opening, please confirm:

- [X] I have checked to see if my question is addressed in the [FAQ](https://github.com/aws-amplify/amplify-hosting/blob/master/FAQ.md).
- [X] I have [searched for duplicate or closed issues](https://github.com/aws-amplify/amplify-hosting/issues?q=is%3Aissue+).
- [X] I have removed any sensitive information from my code snippets and submission.

### Amplify Hosting feature

Environment variables

### Is your feature request related to a problem? Please describe:

Hey team! So, right now, setting up environment variables in AWS Amplify is a bit of a hassle. You have to manually enter each variable one by one, which can be super time-consuming and prone to errors. It's especially annoying when you have a lot of environment variables to deal with. Think about the times you've used DigitalOcean – it's a breeze there because you can just copy and paste the whole .env file at once

https://github.com/user-attachments/assets/2a9786c2-a838-47c3-8e3c-d242c07379bb

### Describe how you'd like this feature to work

I propose adding a feature to the AWS Amplify console that allows users to copy and paste their entire .env file content at once. This would significantly streamline the setup process for environment variables, reducing the chance of human error and saving valuable time.

Implementation Details:

- Add a text area input in the environment variable setup section where users can paste their .env file content.
- Automatically parse the pasted content and populate the environment variables accordingly.
- Ensure that the parsing process handles different formats and edge cases (e.g., comments, blank lines).
- Provide clear feedback to the user on successful parsing and any errors encountered.

This feature will make AWS Amplify more user-friendly and align it with the convenience offered by other platforms

Start in the AWS Amplify console's environment variable setup section and trace how variables are currently entered. Define the .env parsing behavior for comments, blank lines, formats, and errors, then verify that pasted content populates the variables and gives clear success or failure feedback.

Written by the indexing model from the issue text.