remove flatc-generated files from source
Reassigned to Quentin, the poc of https://github.com/tensorflow/tensorflow/issues/62298. That would be great, but those files are needed for the CMake build that doesn't generate them. It's possible but that will require updating the `CMakeLists.txt` to generate those files.

I think the flabuffer library provides a CMake module to do that. hm, i made a gn proof of concept of that for chromium and i'd say applying [the string replacement](https://github.com/tensorflow/tensorflow/blob/306833457d32dd27a198ec8f6839b4966f941d4d/tensorflow/lite/acceleration/configuration/BUILD#L49) sounds like the most interesting problem here This should be doable with something in the lines of:

```cmake
ADD_CUSTOM_COMMAND(
  OUTPUT "${PROJECT_BINARY_DIR}/configuration.fbs"
  COMMAND flatc --proto -o ${PROJECT_BINARY_DIR} tensorflow/lite/acceleration/configuration/configuration.proto
  COMMAND perl -p -i -e 's/tflite.proto/tflite/' "${PROJECT_BINARY_DIR}/configuration.fbs"
  DEPENDS tensorflow/lite/acceleration/configuration/configuration.proto
  WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
)
``` is perl already a required build dependency for cmake users? It doesn't seem so. The replacement seems fairly simple, maybe a combination of the following will do the trick.
- https://discourse.cmake.org/t/what-is-the-best-way-to-search-and-replace-strings-in-a-file/1879
- https://cmake.cmake.narkive.com/jCO5xK76/string-replacement-without-external-commands-help-ex-sed > I think the flabuffer library provides a CMake module to do that.

some places already use flatc and some don't, and those that do, do it in completely different ways including having different variables for finding flatc, what a mess
they should get generated with flatc as part of the build process, and the bazel workflows are ready for this, but they just aren't. this results in making tflite depend on a very specific revision of flatbuffers.

closes https://github.com/tensorflow/tensorflow/issues/62298