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

[AnirudhPudari]

Why these changes are required ?

• 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

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[AnirudhPudari]

Closing this PR as i have branch commit and pushing issues on my machine so closing it. will raise the PR again