feat: add generator plugin for endpoints returning signals #6566

Job	Run time
Build Java and TypeScript for other tasks	2m 39s
Test Java	3m 57s
Gradle tests (ubuntu-latest)	3m 50s
ITs (ubuntu-latest, group-1)	8m 13s
Gradle tests (windows-latest)	7m 20s
Check style	1m 57s
ITs (windows-latest, group-2)	10m 8s
Test TypeScript	2m 3s
ITs (windows-latest, some)	8m 26s
Tests Summary	6s
	48m 39s

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