SONARJAVA-6304: Implement S8218: Instant APIs should only use supported temporal units - #6039

📄 java-checks/src/main/java/org/sonar/java/checks/UnsupportedChronoUnitWithInstantCheck.java:74-78 📄 java-checks/src/test/java/org/sonar/java/checks/UnsupportedChronoUnitWithInstantCheckTest.java:36-43
onMethodInvocationFound is only invoked after MethodMatchers resolved the invocation against java.time.Instant, which requires semantics; with withoutSemantic() the method symbol is unknown and the callback never fires, so context.getSemanticModel() == null can never be true here. Likewise both matchers declare exactly two parameters, so mit.arguments().size() < 2 is never true. The two conditions are unreachable branches (and test_without_semantic does not actually exercise them); dropping them simplifies the check and avoids uncovered branches.

• ✅ Exclude custom TemporalUnit implementations from reporting
• ✅ Exclude value propagation through variables in the initial implementation
• ✅ Report direct enum constants, including statically imported constants, only when semantic resolution confirms the symbol belongs to java.time.temporal.ChronoUnit