Support all Behavior Annex external-condition logical expressions 🤖

[lwrage]

Summary

Fixes #3166

Behavior Annex external conditions now accept and preserve xor, and then, or else, and recursively parenthesized event-trigger expressions.

Cause and correction

ModeSwitchCondition previously represented only OR-separated conjunctions of reference leaves. It therefore could not parse grouping or retain the complete D.7 logical-operator set.

The grammar now stores the operator at both precedence levels and introduces recursive mode-switch triggers. The strict BA model mirrors that structure, and DeclarativeToStrictTranslator preserves each operator and nested group while resolving event and event-data ports. EMF and Xtext artifacts were regenerated, and the #3166 conformance expectations and characterization goldens are updated.

Regression coverage

Issue3166Test models one external condition combining ordinary, exclusive, and short-circuit operators with a parenthesized group. It verifies:

• exact declarative expression structure;
• exact strict-model structure and operator values;
• event and event-data port resolution;
• unparse and reparse preservation.

The existing ExternalConditionXor.aadl and ExternalConditionGrouping.aadl conformance expectations are enabled.

Validation

All Maven commands used -T5.

• Focused Issue3166Test: 2 tests, 0 failures, 0 errors, 0 skipped.
• BehaviorAnnexConformanceTest: 12 tests, 0 failures, 0 errors, 2 existing tracked skips.
• Full org.osate.ba.tests suite: 133 tests, 0 failures, 0 errors, 2 existing tracked skips.
• Clean root reactor with -Dtycho.localArtifacts=ignore: all 143 modules succeeded in 2:15.

Dependencies and residual risk

No dependent PRs; this branch is based directly on origin/master at 7fb3251c3a. The broad generated-parser diff is the output of the manual Xtext generation step. Downstream BA, Xtext integration, graphical editor, and complete root-reactor validation passed.