[ossfuzz] Improve the fuzzers

[ossfuzz] Improve the fuzzers

* Run more decompression variants
* Round trip the compression fuzzer and do partial decompression as well
* Add a compression fuzzer that compresses into a smaller output buffer
  and test the destSize variant

These fuzzers caught 2 bugs that were fixed in the previous commit.
* Input buffer over-read in partial decompress
* Partial decompress fails if output size is 0