UI fixes and UX updates

[ryuash]

Description

closes #131

Other unrelated ux/ui updates

• updated post comments ui (the content shifts to be under the name instead of starting at the icon)
• 
• fixed the empty containers to be same across screens
• Postlist is no longer reloaded when user toggles between the two screens (home and account allowing it to keep its scroll position on postlists) (#131)
• implemented scrollToTop (#131)
• If user is already on top and clicks the home tab again the posts will refresh (#131)

Checklist

• [x] Targeted PR against correct branch.
• [x] Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• [x] Wrote unit tests.
• [x] Run flutter format.
• [ ] Updated the documentation.
• [ ] Added an entry to the CHANGELOG.md file.
• [x] Re-reviewed Files changed in the Github PR explorer.

[codecov[bot]]

Codecov Report

Merging #143 into master will decrease coverage by 0.06%. The diff coverage is 61.94%.

@@            Coverage Diff             @@
##           master     #143      +/-   ##
==========================================
- Coverage   63.79%   63.72%   -0.07%     
==========================================
  Files         277      277              
  Lines        7087     7157      +70     
==========================================
+ Hits         4521     4561      +40     
- Misses       2566     2596      +30     

Impacted Files	Coverage Δ
lib/entities/mnemonic/mnemonic_data.dart	77.77% <ø> (ø)
...ities/notifications/transaction_notifications.dart	92.30% <ø> (ø)
lib/entities/posts/link_preview.dart	4.76% <0.00%> (ø)
lib/entities/posts/polls/poll_answer.dart	53.84% <ø> (ø)
lib/entities/posts/polls/poll_option.dart	53.84% <0.00%> (ø)
lib/entities/posts/post_status.dart	76.00% <ø> (ø)
lib/entities/user/user.dart	96.42% <ø> (ø)
lib/entities/user/user_image.dart	97.50% <ø> (ø)
lib/sources/chain/models/msgs/chain_poll_data.dart	0.00% <ø> (ø)
...b/sources/chain/models/msgs/chain_poll_option.dart	0.00% <ø> (ø)
... and 136 more

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[ryuash]

Put this on hold real quick. Found some ux errors.