[Issue #9101][Function]Fixed get function info error

[tuteng]

Fixes: #9101

Motivation

curl http://localhost:8080/admin/v3/functions/public/default/function-name

org.glassfish.jersey.message.internal.WriterInterceptorExecutor$TerminalWriterInterceptor aroundWriteTo
SEVERE: MessageBodyWriter not found for media type=text/plain, type=class org.apache.pulsar.common.functions.FunctionConfig, genericType=class org.apache.pulsar.common.functions.FunctionConfig.

Modifications

• Add annotations @Produces(MediaType.APPLICATION_JSON) and @Consumes(MediaType.APPLICATION_JSON)
• Update function name from listSources to listFunctions

Verifying this change

• Make sure that the change passes the CI checks

Does this pull request potentially affect one of the following parts:

If yes was chosen, please highlight the changes

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API: (yes / no)
• The schema: (yes / no / don't know)
• The default values of configurations: (yes / no)
• The wire protocol: (yes / no)
• The rest endpoints: (yes / no)
• The admin cli options: (yes / no)
• Anything that affects deployment: (yes / no / don't know)

Documentation

• Does this pull request introduce a new feature? (yes / no)
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)
• If a feature is not applicable for documentation, explain why?
• If a feature is not documented yet in this PR, please create a followup issue for adding the documentation

[sijie]

/pulsarbot run-failure-checks

[sijie]

/pulsarbot run-failure-checks

[wolfstudy]

/pulsarbot run-failure-checks