shared httpRequest method

It may be useful to share the schema-registry httpRequest method (in RestUtils) by moving it to common

Start by reading the RestUtils implementation and locating the schema-registry httpRequest method mentioned in the issue. Determine whether the method can be moved into this common utilities library without losing its callers; done means the shared method is available from common and the schema-registry usage is updated.

Written by the indexing model from the issue text.