Update Copyright Headers 'Facebook' -> 'Meta Platforms'

```
for f in $(find . \( -path ./.git -o -path ./tests/fuzz/corpora \) -prune -o -type f);
do
  sed -i 's/Facebook, Inc\./Meta Platforms, Inc. and affiliates./' $f;
done
```

doc/zstd_compression_format.md

@@ -3,7 +3,7 @@ Zstandard Compression Format
 
 ### Notices
 
-Copyright (c) 2016-2021 Yann Collet, Facebook, Inc.
+Copyright (c) 2016-2021 Yann Collet, Meta Platforms, Inc. and affiliates.
 
 Permission is granted to copy and distribute this document
 for any purpose and without charge,