Adds a panel for displaying notes

[drustanyjt]

Closes #95. This PR covers:

• UI changes to display notes in a side panel.
• find command changes the note displayed.

[codecov]

Codecov Report

Attention: Patch coverage is 62.50000% with 12 lines in your changes are missing coverage. Please review.

Project coverage is 71.46%. Comparing base (42166f4) to head (ae41ab8).
Report is 17 commits behind head on master.

Files	Patch %	Lines
src/main/java/seedu/address/ui/MainWindow.java	0.00%	4 Missing ⚠️
src/main/java/seedu/address/ui/NoteDisplay.java	0.00%	4 Missing ⚠️
...rc/main/java/seedu/address/model/ModelManager.java	81.25%	2 Missing and 1 partial ⚠️
...rc/main/java/seedu/address/logic/LogicManager.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #121      +/-   ##
============================================
- Coverage     71.63%   71.46%   -0.18%     
- Complexity      471      479       +8     
============================================
  Files            78       79       +1     
  Lines          1622     1654      +32     
  Branches        160      160              
============================================
+ Hits           1162     1182      +20     
- Misses          400      411      +11     
- Partials         60       61       +1     

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[Jayne1010]

LGTM!