[pulsar-functions] Add maximum allowed amount of resources setting for functions

[fantapsody]

Motivation

The pulsar cluster may not allow users to request an arbitrary amount of resources for functions for various reasons, like quotas, limited physical resources, etc. And it's better to check the function creation requests and explicitly reject those of which the resources requested are greater than allowed.

Modifications

Add a worker config to set the maximum amount of resource a function must request

Verifying this change

• Make sure that the change passes the CI checks.

This change added tests and can be verified as follows:

• Added unit tests to verify the configurations and checks.

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

• 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

A sample configuration has been added to conf/functions_worker.yml.

[sijie]

@freeznet @nlu90 can you review this pull request?

[eolivelli]

Very useful

LGTM

[nlu90]

LGTM