Migrate to null safety

[gladson97]

Description

Migrated To Null Safety.
Recreated Example Project to Null safety

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Run Example Project

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My changes generate no new warnings
• I have checked my code and corrected any misspellings
• I Have Worked only on Dart side of app and migrated to nullsafety.
• I Have Confirmed Working of app in Android

[rohansohonee]

Hi @gladson97

Thanks for the PR.

Here are my observations after viewing your commits:

• The null safety migration for this plugin only requires the environment sdk to be bumped to 2.12.0.
• The example project cannot be migrated yet since one dependency as of writing today is not null safe. (flutter_xlider).
• Please do not commit generated files or platform code files since they are not part of null safety.

So you only need to include a commit with environment sdk version bump to enable plugin to be null safe.
Use like this ">=2.12.0 <3.0.0" (double quote) instead of '>=2.12.0 <3.0.0' (single quote). This is to keep it consistent is all.