Using constants to avoid the use of hardcoded values

[Invokedzz]

Description

The use of hardcoded values is not good for a code that needs to be maintainable.
Therefore, I used the Constants.class with its values to remove a bunch of hardcoded strings.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)
• Performance improvement
• Test coverage improvement

Changes Made

• Removed hardcoded strings, using constants instead
• Added more tests to ConstantsTest.class, to make sure these constants are correct

Testing

• All existing tests pass
• Added new tests for changes
• Tests cover edge cases and spec compliance

Pre-submission Checklist

• My code follows the project's coding standards
• I have run code formatting/linting tools
• I have added tests that prove my fix/feature works
• New and existing tests pass locally
• I have updated documentation if needed
• I have reviewed the TOON specification for relevant sections

Breaking Changes

• No breaking changes
• Breaking changes (describe migration path below)

[github-actions]

Code Coverage

Overall Project	99.05%	🍏
Files changed	100%	🍏

File	Coverage
DecodeHelper.java	100%	🍏
HeaderFormatter.java	100%	🍏
ListItemEncoder.java	100%	🍏
PrimitiveEncoder.java	100%	🍏
ObjectEncoder.java	100%	🍏
ArrayEncoder.java	100%	🍏
LineWriter.java	100%	🍏
Constants.java	100%	🍏
ValueDecoder.java	99.4%	🍏
TabularArrayDecoder.java	99.33%	🍏
ArrayDecoder.java	99.23%	🍏
KeyDecoder.java	98.84%	🍏
ListItemDecoder.java	96.43%	🍏
Flatten.java	94.72%	🍏
PrimitiveDecoder.java	93.27%	🍏