Implement Remark Command according to AB3 Tutorial

[MAOXIONGKAI]

Implemented Remark command in the following format:

remark [index] r/[remark]

which allows user to modify remark of any existing contact in the address book

[codecov]

Codecov Report

Attention: Patch coverage is 62.82051% with 29 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...eedu/address/logic/parser/RemarkCommandParser.java	0.00%	9 Missing ⚠️
.../java/seedu/address/model/util/SampleDataUtil.java	0.00%	6 Missing ⚠️
...c/main/java/seedu/address/model/person/Remark.java	58.33%	3 Missing and 2 partials ⚠️
...java/seedu/address/logic/commands/EditCommand.java	40.00%	3 Missing ⚠️
...in/java/seedu/address/logic/parser/ParserUtil.java	0.00%	3 Missing ⚠️
...main/java/seedu/address/commons/core/Messages.java	0.00%	1 Missing ⚠️
.../seedu/address/logic/parser/AddressBookParser.java	0.00%	1 Missing ⚠️
src/main/java/seedu/address/ui/PersonCard.java	0.00%	1 Missing ⚠️

Files with missing lines	Coverage Δ	Complexity Δ
src/main/java/seedu/address/logic/Messages.java	88.88% <100.00%> (+1.38%)	3.00 <0.00> (ø)
...va/seedu/address/logic/commands/RemarkCommand.java	100.00% <100.00%> (ø)	10.00 <10.00> (?)
...a/seedu/address/logic/parser/AddCommandParser.java	100.00% <100.00%> (ø)	5.00 <0.00> (ø)
...ain/java/seedu/address/logic/parser/CliSyntax.java	85.71% <100.00%> (+2.38%)	1.00 <0.00> (ø)
...c/main/java/seedu/address/model/person/Person.java	97.43% <100.00%> (+0.21%)	20.00 <1.00> (+1.00)
.../java/seedu/address/storage/JsonAdaptedPerson.java	100.00% <100.00%> (ø)	12.00 <0.00> (+1.00)
...main/java/seedu/address/commons/core/Messages.java	0.00% <0.00%> (ø)	0.00 <0.00> (?)
.../seedu/address/logic/parser/AddressBookParser.java	90.47% <0.00%> (-9.53%)	12.00 <0.00> (ø)
src/main/java/seedu/address/ui/PersonCard.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...java/seedu/address/logic/commands/EditCommand.java	93.90% <40.00%> (-3.54%)	13.00 <0.00> (ø)
... and 4 more