Clean up some old technical debt: Move FixedPoint from third_party/eigen3 to  third_party/tensorflow. The fixed point library is not a part of or used by Eigen, but was developed for TensorFlow and never pushed to Eigen upstream.

This also simplifies the TF open source build: After this change tensorflow/third_party/eigen3/... consists entirely of forwarding headers (and can perhaps be removed?)

PiperOrigin-RevId: 478097075
Change-Id: Ie4785af12387ec430b73406451e01a4afae2cce3
11 files changed