BugFix onboarding

[FHellmann]

Short description of what this resolves:

It fixes the IllegalStateException of the onboarding.

Changes proposed in this pull request:

• Replace onboarding library
• Only track launchable apps
• BugFixes

Does this close any currently open issues?

Fix #96

[codecov[bot]]

Codecov Report

Merging #97 into master will increase coverage by 29.9%. The diff coverage is 70.97%.

@@            Coverage Diff             @@
##           master      #97      +/-   ##
==========================================
+ Coverage   24.44%   54.35%   +29.9%     
==========================================
  Files          75       85      +10     
  Lines        1530     1700     +170     
  Branches       61       62       +1     
==========================================
+ Hits          374      924     +550     
+ Misses       1154      741     -413     
- Partials        2       35      +33

Impacted Files	Coverage Δ
...sburg/uniatron/ui/MainActivityCardListAdapter.java	73.52% <ø> (+73.52%)	:arrow_up:
...com/edu/uni/augsburg/uniatron/ui/MainActivity.java	36.08% <ø> (+36.08%)	:arrow_up:
...m/edu/uni/augsburg/uniatron/ui/card/DateCache.java	100% <ø> (+100%)	:arrow_up:
...rg/uniatron/notification/NotificationChannels.java	45.45% <ø> (ø)	:arrow_up:
.../augsburg/uniatron/ui/setting/SettingFragment.java	0% <ø> (ø)	:arrow_up:
.../uniatron/service/NotificationReceiverService.java	0% <0%> (ø)	:arrow_up:
...gsburg/uniatron/ui/card/appusage/AppUsageCard.java	0% <0%> (ø)	:arrow_up:
...burg/uniatron/ui/shop/TimeCreditShopViewModel.java	0% <0%> (ø)	:arrow_up:
...augsburg/uniatron/ui/setting/SettingViewModel.java	0% <0%> (ø)	:arrow_up:
...augsburg/uniatron/ui/card/summary/SummaryCard.java	0% <0%> (ø)	:arrow_up:
... and 61 more