Deleting a Pulsar Function with a name that includes a colon character crashes the pulsar broker

[csthomas1]

Describe the bug
I'm able to successfully deploy in Pulsar a Pulsar function that includes a ':' as part of its function name. When I later try to delete the function deployment, the Pulsar broker ends up crashing with an IllegalArgumentException in its log stating "Invalid format for fully qualified instance name: :". If the KubernetesRuntime is configured, this prevents deletion of the function's statefulset.

The bug can be found in the class org.apache.pulsar.function.utils.FunctionInstanceId within the pulsar-function-utils library -- it relies on a ':' as a delimiter to separate the function name from the instance id, and in so doing assumes that there can only be at most one ':' in the function name.

This has been observed on both Pulsar 2.6.0 and Pulsar 2.7.0.

To Reproduce
Steps to reproduce the behavior:

1. Use pulsar-admin to deploy a function. Specify a function name that includes a ':'. Example:

pa functions create --fqfn platform/passthrough2/test:input:filter -i persistent://public/default/input -o persistent://public/default/output --jar /tmp/test-functions-1.0.0-SNAPSHOT.jar --classname messaging.pulsar.functions.PassThroughFilter

2. Wait until the function is running, then try to delete the function. Example:

pa functions delete --fqfn platform/passthrough2/test:input:filter

3. Check the status of whichever broker received the request to remove the function instance. You should see evidence of a crash. In the logs you'll see the following message:

java.lang.IllegalArgumentException: Invalid format for fully qualified instance name: platform/passthrough2/test:input:filter

Expected behavior

Since pulsar accepts a function name that includes ':' during creation, it should support it during deletion as well.

Additional context
Pull request incoming...