Editw tests

[VedJoshi]

• New tests for Editw and parser
• Model stubs now in testutil
• Checkstyle fixes

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Files with missing lines	Coverage Δ	Complexity Δ
...ava/seedu/address/logic/commands/EditwCommand.java	75.60% <100.00%> (+75.60%)	7.00 <0.00> (+7.00)
...seedu/address/logic/parser/EditwCommandParser.java	85.00% <100.00%> (+85.00%)	6.00 <1.00> (+6.00)

... and 11 files with indirect coverage changes