Add "changed" status, refactor

[IonBazan]

This PR introduces new operation type: Changed which represents an operation where at least one of the components is referencing a branch/commit or a version constraint (for platform dependencies).

Among with the refactoring, there are following breaking changes:

• PackageDiff::getPackageDiff() now returns DiffEntries instead of array
• Formatters use DiffEntries instead array too
• When it's not possible to normalize the version (for example in platform dependencies, when version constraint is used), the operation is now "changed" instead of "upgraded"
• All dev- version changes are treated as Changed instead of Upgraded which slightly differs from Composer output (which uses more sophisticated method to decide whether it's upgrade or downgrade - for example, any dev-master -> dev-branch will be treated as downgrade)

[codecov]

Codecov Report

Merging #6 (b44fcd2) into master (4fcbe58) will not change coverage.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##              master        #6   +/-   ##
===========================================
  Coverage     100.00%   100.00%           
- Complexity       141       162   +21     
===========================================
  Files             16        19    +3     
  Lines            386       430   +44     
===========================================
+ Hits             386       430   +44     

Impacted Files	Coverage Δ
src/Composer/Plugin.php	100.00% <ø> (ø)
src/Command/DiffCommand.php	100.00% <100.00%> (ø)
src/Diff/DiffEntries.php	100.00% <100.00%> (ø)
src/Diff/DiffEntry.php	100.00% <100.00%> (ø)
src/Diff/VersionComparator.php	100.00% <100.00%> (ø)
src/Formatter/AbstractFormatter.php	100.00% <100.00%> (ø)
src/Formatter/JsonFormatter.php	100.00% <100.00%> (ø)
src/Formatter/MarkdownListFormatter.php	100.00% <100.00%> (ø)
src/Formatter/MarkdownTableFormatter.php	100.00% <100.00%> (ø)
src/PackageDiff.php	100.00% <100.00%> (ø)
... and 3 more

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[IonBazan]

@trakos Please check if this solves your issue. Comparing these dev- parts is quite tricky so let me know if it's returning an expected result. Please check the test cases for more info.

[trakos]

@IonBazan thanks a lot, yes it does :) I use composer 2, and it shows Changed as expected for dev- versions.

I've also checked the test cases I mentioned in the issue and it shows Changed for all of them :)

[IonBazan]

Good to hear! I am still thinking about implementing custom version comparison logic instead of using VersionParser and Semver as they produce slightly different results between different Composer versions to make it more consistent. The thing is that there is tons of logic behind it so I will most probably leave it as is. That's because the operation name is not that important as showing correct base and target versions.