Add the ability to transform an existing non-partitioned to a partitioned topic without deleting it.

[disserakt]

Context:
At the moment we cannot change the topic type from non-partitioned to partitioned for topics that already exist and contain data. Such topics can now only be deleted and created as partitioned.
In this case, we lose data.
In order to keep the existing data in topics, it is highly desirable to have a way to transform the topic type from non-partitioned to partitioned and vice versa.

Desirable solution:
For example, for the command - pulsar-admin topics, create a key - transform-type, with flags:

--to-non-partitioned
--to-partitioned

which will allow us to transform the topic type.

[codelipenghui]

The issue had no activity for 30 days, mark with Stale label.

[brunocascio]

Any idea about how to do this?