Express existing okhttp dependency manipulation at project wide scope

[k-wall]

okhttp version is now consistent across all its modules

mvn dependency:tree   | grep com.squareup.okhttp3
[INFO] \- com.squareup.okhttp3:okhttp:jar:4.12.0:compile
[INFO] \- com.squareup.okhttp3:okhttp:jar:4.12.0:compile
[INFO] \- com.squareup.okhttp3:okhttp:jar:4.12.0:compile
[INFO] \- com.squareup.okhttp3:okhttp:jar:4.12.0:compile
[INFO] |  \- com.squareup.okhttp3:logging-interceptor:jar:3.12.12:compile
[INFO] +- com.squareup.okhttp3:mockwebserver:jar:4.12.0:test
[INFO] \- com.squareup.okhttp3:okhttp:jar:4.12.0:compile
[INFO] |  |  \- com.squareup.okhttp3:logging-interceptor:jar:3.12.12:provided
[INFO] +- com.squareup.okhttp3:mockwebserver:jar:4.12.0:test
[INFO] \- com.squareup.okhttp3:okhttp:jar:4.12.0:compile
[INFO] \- com.squareup.okhttp3:okhttp:jar:4.12.0:compile
[INFO] \- com.squareup.okhttp3:okhttp:jar:4.12.0:compile
[INFO] |  |  \- com.squareup.okhttp3:logging-interceptor:jar:3.12.12:provided
[INFO] \- com.squareup.okhttp3:okhttp:jar:4.12.0:compile
[INFO] \- com.squareup.okhttp3:okhttp:jar:4.12.0:compile
[INFO] \- com.squareup.okhttp3:okhttp:jar:4.12.0:compile
[INFO] |  |  \- com.squareup.okhttp3:logging-interceptor:jar:3.12.12:compile
[INFO] \- com.squareup.okhttp3:okhttp:jar:4.12.0:compile
[INFO] \- com.squareup.okhttp3:okhttp:jar:4.12.0:compile

when in jdk mode, the only okhttp3 dependency is a test one, on the mockwebserver. (There's a compile time dependency on mockwebserver (org.apache.flink.kubernetes.operator.TestUtils), so we can't make that dependency's inclusion based on the profile).

mvn dependency:tree  -Dfabric8.httpclient.impl=jdk -P'!depend-on-okhttp4' | grep com.squareup.okhttp3
mvn dependency:tree  -Dfabric8.httpclient.impl=jdk -P'!depend-on-okhttp4' | grep com.squareup.okhttp3
[INFO] +- com.squareup.okhttp3:mockwebserver:jar:4.12.0:test
[INFO] |  +- com.squareup.okhttp3:okhttp:jar:4.12.0:test
[INFO] \- com.squareup.okhttp3:mockwebserver:jar:4.12.0:test
[INFO]    +- com.squareup.okhttp3:okhttp:jar:4.12.0:test

I gave the unit tests a spin locally both with and without depend-on-okhttp4. All is green for me.