Replaced Toasts With Snackbars in AchievementsFragment and Leaderboard

[shankarpriyank]

Description (required)

Fixes #2388

What changes did you make and why?
Replaced Toasts With Snackbars in AchievementsFragment and Leaderboard

[shankarpriyank]

It's a bit weird, the tests which are failing in the CI are passing when I test them locally.

[shankarpriyank]

Also, the achievement, leaderboard, and contribution fragments are loading and showing relevant information in the beta flavor, which I guess is not the intended behaviour

[nicolas-raoul]

I think that our achievements calculation server use the production server directly and has no beta version, it was deemed acceptable since it is read-only.

[shankarpriyank]

I think that our achievements calculation server use the production server directly and has no beta version, it was deemed acceptable since it is read-only.

Okay, but we still need to fix the tests..

[shankarpriyank]

@nicolas-raoul could use some help here

[rohit9625]

As we have defined Snackbar functions in file Util.java. So, it would help if you used them as Snackbars.
@shankarpriyank