Add support for Kotlin functions

[sdeleuze]

This PR adds:

• Support for Kotlin functions
• A Kotlin extension to FunctionCallbackWrapper.Builder
• Kotlin documentation for language specifics

It also removes the dependency on Spring Cloud Function and net.jodah:typetools which are replaced by leveraging
Spring Framework RootBeanDefinition and ResolvableType capabilities.

[sdeleuze]

@markpollack Forced-pushed to remove a RootBeanDefinition cast which was not needed and rebased to fix a merge-conflict.

[markpollack]

merged in 9cf6633

[sdeleuze]

Reopening the PR after finding a regression and reverting related commit from main.

[sdeleuze]

I spent some time debugging the initial version of this PR that we had to revert after a regression detailed in #1685 and reproducible with @ThomasVitale repro.

The reason why our tests did not catch this regression is not straightforward. In our tests, ConfigurationClassParser is creating AnnotationMetadata via reflection (StandardAnnotationMetadata) and with that, beanDefinition.getResolvableType() works as expected because the function type is resolved via RootBeanDefinition#factoryMethodToIntrospect but in the application that reproduces the issue, the AnnotationMetadata is a SimpleAnnotationMetadata created via ASM where beanDefinition.getResolvableType() is unable to resolve the type.

Generally speaking, BeanDefinition#getResolvableType() is a sort of best-effort representation of the currently known time information at runtime, so I have added a fallback resolution using the factory method, duplicating (for now) ConstructorResolver#resolveFactoryMethodIfPossible logic which is not exposed in the public API. We may expose that in a future version of Spring Framework.

I have added related tests using tests that involve scanning to trigger the ASM code path. Both tests and @ThomasVitale repro are green with that new version I forced pushed, and Open AI IT tests seems to be fine as well.

There still may be some small differences with original SCF algorithm, but I guess we could refine with proper test if something is not supported yet.

[sdeleuze]

Notice that suspending functions are not yet supported a discussed in that comment.

[tzolov]

rebased, squashed and merged at c3c95a8