feat: Add support for SelectableText widget

[divyanshub024]

Description

Add support for the SelectableText widget in Stac, enabling developers to declare selectable text in Server Driven UI for Flutter apps. This widget will allow displaying material design selectable text elements as described in the official documentation: Flutter SelectableText Widget.

Requirements

• Create a model for the SelectableText widget in the stac_core package.
• Add a parser for the SelectableText widget in the stac package.
• Create an example in Stac Gallery.
• Add documentation for the SelectableText widget.

Additional Context

Selectable text fields improve accessibility and allow users to interact with textual content more flexibly. See API for widget details: https://api.flutter.dev/flutter/material/SelectableText-class.html

[xkaper001]

Hey @divyanshub024, I'd love to work on this. Please assign this issue to me.

[divyanshub024]

Thank you @xkaper001!! I've assigned the issue to you. Feel free to reach out if you need any help 🙌🏻

[divyanshub024]

Hey @xkaper001 !! Any update on this issue? Let us know if you need any help.

[xkaper001]

Hey I've been busy lately, I'll raise the PR in a day or two.