patch 9.2.0418: wildcards in expanded env vars reinterpreted by glob

patch 9.2.0418: wildcards in expanded env vars reinterpreted by glob

Problem:  With $d='[dir]', `:e $d/file.txt` opens the wrong file,
          `:e $d/<Tab>` fails to complete, and `glob('$d/*')` returns
          nothing. Wildcard characters inside expanded environment
          variables get picked up by globbing again.
Solution: Turn the 4th parameter of expand_env_esc() from a bool into a
          string of characters to escape in each expanded value. Callers
          that pass the result to wildcard expansion should include
          PATH_ESC_WILDCARDS in addition to " \t" (glepnir).

closes: #20053

Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>