Problem: There is no way to get a list of swap file names.
Solution: Add the swapfilelist() function. Use it in the test script to
clean up. Remove deleting individual swap files.
c216a7a21a
vim-patch:9.0.1005: a failed test may leave a swap file behind
Problem: A failed test may leave a swap file behind.
Solution: Delete the swap file to avoid another test to fail. Use another
file name.
d0f8d39d20
Cherry-pick test_window_cmd.vim changes from patch 8.2.1593.
Remove FUNC_ATTR_UNUSED from eval functions as fptr is always unused.
Co-authored-by: Bram Moolenaar <Bram@vim.org>