Create pop-up window for View command

[itsnotsherm]

close #52

[codecov]

Codecov Report

Attention: Patch coverage is 19.04762% with 34 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/main/java/seedu/address/ui/ViewWindow.java	0.00%	22 Missing ⚠️
src/main/java/seedu/address/ui/MainWindow.java	0.00%	10 Missing ⚠️
...java/seedu/address/logic/commands/ViewCommand.java	0.00%	2 Missing ⚠️

Files with missing lines	Coverage Δ	Complexity Δ
src/main/java/seedu/address/logic/Messages.java	88.88% <ø> (ø)	3.00 <0.00> (ø)
...va/seedu/address/logic/commands/CommandResult.java	100.00% <100.00%> (ø)	15.00 <4.00> (+2.00)
...java/seedu/address/logic/commands/ExitCommand.java	100.00% <100.00%> (ø)	2.00 <1.00> (ø)
...java/seedu/address/logic/commands/HelpCommand.java	100.00% <100.00%> (ø)	2.00 <1.00> (ø)
...java/seedu/address/logic/commands/ViewCommand.java	84.21% <0.00%> (-15.79%)	7.00 <0.00> (-1.00)
src/main/java/seedu/address/ui/MainWindow.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
src/main/java/seedu/address/ui/ViewWindow.java	0.00% <0.00%> (ø)	0.00 <0.00> (?)

[reidenong]

LGTM, code looks clean. No issues with checks either.