Pull to refresh doesn't work when there are no tasks

[AnirudhPudari]

Why these changes are required ?

Issue link

• Currently on the task list screen when the content is empty or no tasks, pull to refresh doesn't work(it is not shown at all after you swipe down vertically)
• Reason is the empty container shown doesn't contain pull to refresh
• Exisiting SwipeRefresh is deprecated

What changes are addressed ?

• Addressed the issue of showing a pull to refresh spinner both when the content is empty and not empty
• Migrated SwipeRefresh to PullRefreshIndicator as suggested

todo_test.webm

[dturner]

Please fix the spotless formatting.

[AnirudhPudari]

Please fix the spotless formatting.

@dturner Hi, I have addressed the issue, Please review PR. Thank you