Use SharedPreferences to store whether the user has already seen the app onboarding screen

[wsloth]

The onboarding screen was introduced in PR #12, but it does not retain a boolean for whether the user has already seen the onboarding screen.

To do:

• Install the Shared Preferences package
• After the onboarding screen has been shown, store a boolean value
• When re-opening the app, evaluate whether the boolean is present and skip the onboarding screen

Anybody can pick this up, no assignments necessary. Let me know if I need to provide more info!

[REX51]

Hey @wsloth I would like to work on this

[wsloth]

@REX51 thanks for taking interest, feel free to pick up this issue!

[REX51]

@wsloth checkout my PR #16
I have added shared preferences and permission handler to get access to local storage to store the shared preferences.
User will be prompted to "allow/deny" access to local storage for the very first time loading the app, once it is allowed, on boarding screen will load only once for the user.

[REX51]

Hey @wsloth let me know if anything is required from my end #16

[wsloth]

Sorry for the delay @REX51, I was really busy at work! Your changes look and work great, thanks for your contribution! 👏