Bug#848049: diffoscope: Add detection for order only differnce by lines

[Emanuel Bronshtein]

Package: diffoscope
Severity: wishlist

Please add detection of order only variations in plain text files (TXT/HTML files)
in similar way like the recent addition of order only difference in JSON output in:
https://anonscm.debian.org/cgit/reproducible/diffoscope.git/commit/?id=8faf040767b892e1cf19d4ec2965a29301b9ae40

Thus allows easier/faster classification of issues, for example the below issues:

random_order_in_md5sums
clilibs_line_order
varying_ordering_in_data_tar_gz_or_control_tar_gz
random_order_in_tarball
qt_translate_noop_nondeterminstic_ordering
random_order_in_ibus_table_createdb_output
db_ordering_noop_detect
random_ordering_in_pom
random_order_in_sisu_javax_inject_named
sphinx_htmlhelp_readdir_sensitive
nondeterminstic_ordering_in_gsettings_glib_enums_xml
valac_permutes_get_type_calls

share the same 'order only difference', it can be implemented by merging all the changed lines in file A (first build) vs same file B (second build), if there is the same amount of lines it's means that there is no other difference except ordering.