Remove OpenJPEG logs from the JPX fuzzer output

[timvandermeij]

The JPX fuzzer currently spams the output with the following log lines:

OpenJPEG: Unknown format

The JPX code does nicely emit a JpxError exception that we catch and handle, but it looks like the C code additionally prints this to the console. We should check if we can disable that somehow, most likely in our C wrapper code (but otherwise doing this in the fuzzer code somehow would probably also suffice).

[timvandermeij]

@calixteman It looks like this originates from https://github.com/mozilla/pdf.js.openjpeg/blob/1cac231daf39bcf4aa70ee363833a710108d578c/src/decoder.c#L64. Could we perhaps replace the direct printing with storing this data in the exception message instead somehow? It would be nice if the raised JpxError in JS contained the "unknown format" bit because then the error message is also more precise, and it gives the caller the possibility to handle the error instead of it being printed unconditionally from the C code. I'm not sure how easy that is from a WebAssembly wrapper though, but I would imagine it should be possible somehow to communicate the error message to JS.

(This would in general be an improvement of the usability of the JpxImage class in Node.js environments, so this is not limited to the fuzzer: the fuzzer only surfaced it.)