could we add some hook method to allow users set header in pulsar-admin-client

**Is your enhancement request related to a problem? Please describe.**
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now , when we use pulsar-admin-client to invoke some rest api

we only add auth header to request, but sometimes ,we want to add some extra headers

**Describe the solution you'd like**

1.

allow client register inteceptor

2. before and after requestAsync method , do some hook method
**Describe alternatives you've considered**
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**Additional context**
Add any other context or screenshots about the feature request here.

Start by locating the pulsar-admin-client implementation of requestAsync and the code that adds the auth header. Review how an interceptor or before/after hook could supply extra headers; the work is done when callers can register a hook and those headers are included in REST API requests.

Written by the indexing model from the issue text.