Add an option to skip operation examples

[wing328]

Add an option to skip operation examples to avoid potential JVM out of memory errors

Closes #6597
Closes #8682
Closes #4398

cc @OpenAPITools/generator-core-team

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[rjtg]

This appears to be the wrong default that is assigned - should be DEFAULT_SKIP_OPERATION_EXAMPLE i suppose

[kvn-shn]

How is this supposed to work? I added <skipOperationExample>true</skipOperationExample> to the Maven plugin (version 5.1.1, using spring generator and the delegate pattern) but the massive String exampleString = "..." is still generated into the XxxApiDelegate interface default method implementations.