Fallback to use the Python API to compress/decompress when the CLI dependency is not installed

[suhaibmujahid]

We use the zstd binary in some places instead of zstandard for some performance gains. However, this becomes an issue when the zstd package is not installed, or the binary location is not listed in PATH.

Example of using the zstd binary through CLI:

bugbug/bugbug/utils.py

Lines 244 to 248 in b6291dc

	def zstd_compress(path: str) -> None:
	if not os.path.exists(path):
	raise FileNotFoundError(errno.ENOENT, os.strerror(errno.ENOENT), path)
	subprocess.run(["zstdmt", "-f", path], check=True)

In this case, we should fallback to using zstandard API if we fail to compress using zstdmt because zstd is not installed.

This will solve the following:

• Missing "zstd" Python package for working with Zstandard compression #3708
• FileNotFoundError: [Errno 2] No such file or directory: 'zstdmt' #3742

[marco-c]

The old code, which was not using zstd, to decompress can be seen in this commit: c079f0f.