Include TSL proto files in the pip package

At least a few proto files have had their sources moved into TSL, and the Pip package currently does not include those proto files. See for instance https://github.com/tensorflow/tensorflow/issues/59514.

More specifically, if you download the pip packages, extract them, and compare tensorflow/core/profiler/protobuf/xplane.proto in TF 2.11 vs TF nightly, all of the pip packages have the proto file:

```
2.10/tensorflow/include/tensorflow/core/profiler/protobuf/xplane.proto
2.11/tensorflow/include/tensorflow/core/profiler/protobuf/xplane.proto
nightly/tensorflow/include/tensorflow/core/profiler/protobuf/xplane.proto
```

But the one in Nightly references a non-existent proto:

```
syntax = "proto3";

package tensorflow.profiler.empty;

import public "tensorflow/tsl/profiler/protobuf/xplane.proto";
```

This needs to get cherry-picked into the 2.12 release branch, or else any plugins that reference proto files that have been moved into TSL will not build.

PiperOrigin-RevId: 507929521

tensorflow/tools/pip_package/setup.py

@@ -305,6 +305,7 @@ headers = (
     list(find_files('*.proto', 'tensorflow/core')) +
     list(find_files('*.proto', 'tensorflow/python')) +
     list(find_files('*.proto', 'tensorflow/python/framework')) +
+    list(find_files('*.proto', 'tensorflow/tsl')) +
     list(find_files('*.def', 'tensorflow/compiler')) +
     list(find_files('*.h', 'tensorflow/c')) +
     list(find_files('*.h', 'tensorflow/cc')) +