[CMake] Renames BUILD files (#6457)

* Renamed build to build.bazel to stop xcode from complaining about it

* Renamed all build to build.bazel

* Fixes small ci issue

src/BUILD.bazel

@@ -1,9 +1,10 @@
+# @unused
+load("@rules_cc//cc:defs.bzl", "cc_binary", "cc_library")
+
 package(
     default_visibility = ["//visibility:private"],
 )
 
-load("@rules_cc//cc:defs.bzl", "cc_binary", "cc_library")
-
 # Public flatc library to compile flatbuffer files at runtime.
 cc_library(
     name = "flatbuffers",