Add Slide Direction Enum to Control Slide-In and Slide-Out Direction on `RotateAnimatedText`

## Description

Currently, the Animated-Text-Kit Flutter package provides a great set of animations for text, including the `RotateAnimatedText`. However, it lacks the ability to control the direction of text slide-in and slide-out animations. This enhancement proposes adding a new enum property to `RotateAnimatedText` to allow users to specify the slide direction.

## Motivation

Adding the ability to control the slide-in and slide-out direction of text animations will provide users with greater flexibility and customization options when using the `RotateAnimatedText` widget. It will make the package even more versatile and adaptable to various design requirements.

## Proposed Solution

1. Introduce a new enum called `SlideDirection` at the top of the `RotateAnimatedText` file to control the direction of text slide-in and slide-out animations.

2. Modify the `RotateAnimatedText` constructor to accept a `slideDirection` property of type `SlideDirection`, allowing users to specify the desired slide direction when creating an instance of `RotateAnimatedText`.

3. Update the `initAnimation` method to use the `slideDirection` property to determine the slide direction for both slide-in and slide-out animations.

4. Ensure that the default behavior matches the current behavior for existing users who don't specify a `slideDirection`.

## Additional Information

This enhancement will enhance the capabilities of the Animated-Text-Kit package, making it more versatile and accommodating to a wider range of design requirements. It can be particularly useful for users who want to control the direction of text animations for creative and engaging UI/UX experiences.

Find the RotateAnimatedText class file in the package. Create a SlideDirection enum with values like left, right, up, down. Add a slideDirection parameter to the constructor, defaulting to maintain current behavior. In initAnimation, adjust the animation controllers to use the chosen direction. Test by running the example app and verifying the slide direction changes.

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