[Bazel Migration] Add dependency on util-core-util to util/util-thrift/src/main/scala/com/twitter/util/
[Bazel Migration] Add dependency on util-core-util to util/util-thrift/src/main/scala/com/twitter/util/

**Problem**

util/util-thrift/src/main/scala/com/twitter/util/ uses class `Codec` from `util-core-util`.
In pants, this was (mistakingly) pulled via transitive dependency, which was not correct.

**Solution**

To add a direct dependency on `util-core-util`.
*Why direct?*: Since it uses the `Codec` class directly, I figured the target really wanted to depend on `util-core-util` directly, and not doing so previously was because pants not being strict enough with the exports.
*Why do we export it?*: Because tests that depend on the changed target need `Codec` to be in the classpath when they compile, but they don't use it directly. Exporting seemed like the right thing to do.

**Result**

Compilation passes in Bazel and Pants.

JIRA Issues: DPB-12610

Differential Revision: https://phabricator.twitter.biz/D516475

twitter/util,twitter/util,twitter/util