Fix importing WAV files with odd chunk sizes

[bs-mwoerner]

Fixes #85466.

The RIFF specification requires a padding byte to be written when a chunk size is not even. The current WAV importer did not include that byte when moving to the next chunk, so the import would fail (read a zero-length file) when the file contained a chunk with an odd size before the actual data chunk.

[akien-mga]

CC @lawnjelly if you want to review and take inspiration to fix your own WAV importer :P

[lawnjelly]

I'm no expert in RIFF files but it does seem like chunks should be padded like this:
https://www.daubnet.com/en/file-format-riff

unused 1 byte present, if size is odd

[bs-mwoerner]

Ah, yes, I could have quoted a source. I got my info from Wikpedia: https://en.wikipedia.org/wiki/Resource_Interchange_File_Format

All chunks have the following format:

• 4 bytes: an ASCII identifier for this chunk (examples are "fmt " and "data"; note the space in "fmt ").
• 4 bytes: an unsigned, little-endian 32-bit integer with the length of this chunk (except this field itself and the chunk identifier).
• variable-sized field: the chunk data itself, of the size given in the previous field.
• a pad byte, if the chunk's length is not even.

[akien-mga]

Same email/account attribution issue on this PR :)

[bs-mwoerner]

Merci. :)

[YuriSizov]

Cherry-picked for 4.2.1.