Problem:    "verbose hi Name" reports incorrect info after ":hi clear".
Solution:   Store the script context. (Antony Scriven, closes vim/vim#6975)
https://github.com/vim/vim/commit/e8df0104985af58ee501a6fbac8ac9f886e84e5a

Also adds src/nvim/testdir/script_util.vim which originates from patch 8.2.1366
(https://github.com/vim/vim/commit/a6296200bd5191bab7efcdcc16c9e79eb498e8e0)
because some tests in test_highlight.vim use it for testing :verbose.
Should merge this and older related patches later.

Also, fix collateral damage to test_options.vim

test_options tests for file name completion in the test directory, but
since we've added a new file, the test output is now different.  This
test is slightly different from upstream anyway, so for now we just add
the file name.  This may change when more upstream patches are added
which alter this test.