Refactor MainActivity Layout and Functionality

[bonig97]

Refactor MainActivity Layout and Functionality

This pull request introduces significant updates to the MainActivity layout and functionality. We've implemented modern design components and file handling techniques to enhance user experience and code maintainability.

Changes

Layout Refactoring with Material Design Components

• ConstraintLayout Guidelines: Introduced guidelines for consistent margins and alignment.
• MaterialButton: Replaced the standard Button with MaterialButton for a modern look and feel.
• TextView Constraints: Modified layout constraints of TextView for better positioning and readability.
• TextInputLayouts: Added TextInputLayouts for improved input field handling.
• Layout Adjustments: Made adjustments to element sizes and constraints for enhanced responsiveness and layout structure.

Modern File Picker and Search Functionality

• ActivityResultLauncher: Transitioned to ActivityResultLauncher for handling file access, replacing manual permission handling.
• Modern File Picker: Implemented Intent.ACTION_OPEN_DOCUMENT for a contemporary file picking approach.
• Search Functionality: Added the ability to count occurrences of a word within the selected file.
• Cleaner Codebase: Removed deprecated permission check methods for enhanced code efficiency.
• Refactored onActivityResult: Updated onActivityResult to manage file selection and text processing efficiently.