`core` improve `FeignUtil` `BaseBuilder` to allow the client to choose the `Feign` logger as well as the `Feign` `LogLevel`

improve `FeignUtil` `BaseBuilder` to allow the client to choose
* its `Feign` logger
* as well as the `Feign` `LogLevel`

see https://github.com/adobe/aio-lib-java/pull/145#discussion_r1094850264

It looks like the Feign Logger API is under refactoring see
* https://github.com/OpenFeign/feign#short-term---what-were-working-on-now-
* https://github.com/OpenFeign/feign/issues?q=is%3Aissue+is%3Aopen+logger+label%3Afeign-12
* https://github.com/OpenFeign/feign/issues/1143

a few Feign logging related articles:
* https://cloud.spring.io/spring-cloud-openfeign/reference/html/#feign-logging
* https://medium.com/@piszu/feign-client-is-not-so-simple-as-we-want-case-study-920e4901e27b

Start with FeignUtil's BaseBuilder and review the linked pull request discussion, then read the referenced Feign logger API material to understand the current logger and LogLevel interfaces. Done means clients can choose both the Feign logger and Feign LogLevel through the builder without being blocked by the ongoing Feign API refactoring.

Written by the indexing model from the issue text.