test/pytest_suite: restore missing fixtures, fix exec bits, add svn:ignore

test/pytest_suite: restore missing fixtures, fix exec bits, add svn:ignore

Bring the pytest suite to parity with the canonical source:

* Add 25 previously-missing test fixture files (deflate images, expires
  placeholders, data PNG, rewrite dbm, ssl .pfa placeholders, .empty
  dir-keepers, headers htaccess) that several module tests require; their
  absence caused spurious 404 failures.

* Set svn:executable on the CGI/shell/perl scripts (and the negotiation
  and xbithack content files that carry the bit upstream) so CGI tests no
  longer fail with 500 on a fresh checkout.

* Stop tracking the .htaccess/htpasswd files that the tests rewrite at run
  time (setenvif/htaccess/.htaccess, autoindex2/dir_broken/.htaccess,
  autoindex2/dir_protected/htpasswd) and add svn:ignore for them, matching
  the original Perl Apache::Test framework which never versioned them.

* Add per-directory svn:ignore for c-module build artifacts, generated
  t/conf configs, generated CGI scripts and runtime dirs, plus a recursive
  svn:global-ignores for Python caches (__pycache__, *.pyc, .venv, etc.).

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1934943 13f79535-47bb-0310-9956-ffa450edef68