Since Fuchsia engineers rarely work within this repo, initialize a lightweight fake @fuchsia_sdk repo rather than distributing the Fuchsia SDK here.
Tested locally via `bazel query --[no]enable_bzlmod "deps(set(//googletest/test:gtest_all_test))"` (#4472)
PiperOrigin-RevId: 610826859
Change-Id: I7d41b1dbe9e7f133fe535d7337dc5bff5bf97d3a
