IssueActivity doesn't remember state of its fragments

[arthur]

Description

IssueActivity doesn't remember the state of its fragments

Versions and device

Android 9
PocketHub v0.5.1
HUAWEI MATE 10

Steps to Reproduce

1. Go to a repository
2. Click “+” to new an issue, and type some things
3. Tap "back"
4. Click “+” to new an issue, nothing saved

Actual behaviour

Not restore data when re-entering IssueActivity.

Expected behaviour

The previous state is restored. Prevents the case that quit by mistake.