7zip reader: add some 7z ARM filter tests

7zip reader: add some 7z ARM filter tests

Note that test_read_format_7zip_lzma2_arm passes, while
test_read_format_7zip_zstd_arm fails, I believe because
liblzma implements these filters internally for itself, unlike the
other compression libraries.

These two archives contain a linux C hello world executable, built for
gnueabihf. They were created like so (the first one using a fork of
7-zip with zstandard support):
7z a -t7z -m0=zstd -mf=ARM libarchive/test/test_read_format_7zip_zstd_arm.7z hw-gnueabihf
and
7z a -t7z -m0=lzma2 -mf=ARM libarchive/test/test_read_format_7zip_lzma2_arm.7z hw-gnueabihf