GH-1773 - Add support for Couchbase

[Fezlight]

Summary

A new events module created spring-modulith-events-couchbase. This module aim to support Couchbase database in a similar way as MongoDB module and also support Transactional.

Couchbase need collections and indexes to be manually created like JDBC-base implementation, so i added some information in appendix.

Fixes #1773

Next

I think a next way can be to auto-configure collections and indexes programmatically using Couchbase SDK like JDBC-based implementation "spring.modulith.events.jdbc.schema-initialization.enabled"

Known issue

There is an issue with the "bootstrapsApplication" test in couchbase epr module with transation propagation level REQUIRE_NEW not being supported for now (See in Scenario). I don't know if Spring modulith use this transaction propagation level somewhere else in the main module ?

java.lang.UnsupportedOperationException: Propagation level 'requires_new' has been specified which is not currently supported

	at org.springframework.data.couchbase.transaction.CouchbaseCallbackTransactionManager.handlePropagation(CouchbaseCallbackTransactionManager.java:227)
	at org.springframework.data.couchbase.transaction.CouchbaseCallbackTransactionManager.execute(CouchbaseCallbackTransactionManager.java:79)
	at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:131)
	at org.springframework.modulith.test.Scenario.lambda$stimulate$1(Scenario.java:169)
	at org.springframework.modulith.test.Scenario.lambda$stimulate$3(Scenario.java:183)
	at org.springframework.modulith.test.Scenario$When.awaitInternal(Scenario.java:415)
	at org.springframework.modulith.test.Scenario$When.andWaitForStateChange(Scenario.java:409)
	at example.ApplicationIntegrationTests.bootstrapsApplication(ApplicationIntegrationTests.java:106)

I will post an issue on spring-data-couchbase to discuss about this (here) . I think it's planned but not already released