runtime(dist): centralize safe executable check and add vim library (vim/vim#13413)

Follow up to 816fbcc26 (patch 9.0.1833: [security] runtime file fixes,
2023-08-31) and f7ac0ef50 (runtime: don't execute external commands when
loading ftplugins, 2023-09-06).

This puts the logic for safe executable checks in a single place, by introducing
a central vim library, so all filetypes benefit from consistency.

Notable changes:
- dist#vim because the (autoload) namespace for a new runtime support
  library. Supporting functions should get documentation. It might make
  life easier for NeoVim devs to make the documentation a new file
  rather than cram it into existing files, though we may want
  cross-references to it somewhere…
- The gzip and zip plugins need to be opted into by enabling execution
  of those programs (or the global plugin_exec). This needs
  documentation or discussion.
- This fixes a bug in the zig plugin: code setting s:tmp_cwd was removed
  in f7ac0ef50 (runtime: don't execute external commands when loading
  ftplugins, 2023-09-06), but the variable was still referenced. Since
  the new function takes care of that automatically, the variable is no
  longer needed.

https://github.com/vim/vim/commit/cd8a3eaf5348feacfecab4b374b7ea4ce6a97422

Co-authored-by: D. Ben Knoble <ben.knoble+github@gmail.com>

runtime(zig): Update Zig runtime files (vim/vim#13388)

Update runtime files from upstream (https://github.com/zig/zig.vim) at
commit 54c216e5306a5c3878a60596aacb94dca8652ab9.

https://github.com/vim/vim/commit/e08bfef88bd05a9d27ee16c57cd10173e280f600

Co-authored-by: Gregory Anders <8965202+gpanders@users.noreply.github.com>

Problem:  Various Typos
Solution: Fix Typos

This is a collection of typo related commits.

closes: vim/vim#12753
closes: vim/vim#13016

https://github.com/vim/vim/commit/ee17b6f70d382ec6c5d8d27b56c4e84106ac8c55

Co-authored-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Adri Verhoef <a3@a3.xs4all.nl>
Co-authored-by: Viktor Szépe <viktor@szepe.net>
Co-authored-by: nuid64 <lvkuzvesov@proton.me>
Co-authored-by: Meng Xiangzhuo <aumo@foxmail.com>
Co-authored-by: Dominique Pellé <dominique.pelle@gmail.com>

runtime: don't execute external commands when loading ftplugins

This is a followup to 816fbcc262687b81fc46f82f7bbeb1453addfe0c (patch
9.0.1833: [security] runtime file fixes)

It basically disables that external commands are run on loading of the
filetype plugin, **unless** the user has set the `g:plugin_exec = 1`
global variable in their configuration or for a specific filetype the
variable g:<filetype>_exec=1.

There are a few more plugins, that may execute system commands like
debchangelog, gitcommit, sh, racket, zsh, ps1 but those do at least
do not run those commands by default during loading of the filetype plugin
(there the command is mostly run as convenience for auto-completion or
to provide documentation lookup).

closes: vim/vim#13034

https://github.com/vim/vim/commit/f7ac0ef5098856bedca26e7073594a407c05636f

Co-authored-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Tim Pope <vim@tpope.org>

runtime(ftplugin): allow to exec if curdir is in PATH

In case the current directory is present as valid $PATH entry, it is OK
to call the program from it, even if vim curdir is in that same
directory.

(Without that patch, for instance, you will not be able to open .zip
files while your current directory is /bin)

closes: vim/vim#13027

https://github.com/vim/vim/commit/67c951df4c95981c716eeedb1b102d9668549e65

Co-authored-by: Anton Sharonov <anton.sharonov@gmail.com>

Problem:  runtime files may execute code in current dir
Solution: only execute, if not run from current directory

The perl, zig and ruby filetype plugins and the zip and gzip autoload
plugins may try to load malicious executable files from the current
working directory.  This is especially a problem on windows, where the
current directory is implicitly in your $PATH and windows may even run a
file with the extension `.bat` because of $PATHEXT.

So make sure that we are not trying to execute a file from the current
directory. If this would be the case, error out (for the zip and gzip)
plugins or silently do not run those commands (for the ftplugins).

This assumes, that only the current working directory is bad. For all
other directories, it is assumed that those directories were
intentionally set to the $PATH by the user.

https://github.com/vim/vim/commit/816fbcc262687b81fc46f82f7bbeb1453addfe0c

Co-authored-by: Christian Brabandt <cb@256bit.org>

runtime: Fix typos in various files

closes: vim/vim#12836

https://github.com/vim/vim/commit/3fc7a7e44abda6505ccd39a6d067db6e5173cbf6

Co-authored-by: Viktor Szépe <viktor@szepe.net>

Update runtime files

https://github.com/vim/vim/commit/86b4816766d976a7ecd4403eca1f8bf6b4105800

vim-patch:9.0.1029: autoload directory missing from distribution

Problem:    Autoload directory missing from distribution.
Solution:   Add the autoload/zig directory to the list of distributed files.

https://github.com/vim/vim/commit/84dbf855fb2d883481f74ad0ccf3df3f8837e6bf

Co-authored-by: Bram Moolenaar <Bram@vim.org>