runtime(vim): Update base-syntax, improve script-interface command highlighting

- Normalise interface heredoc highlighting with that used for
  :let-heredocs.
- Remove interface feature testing.  The Lua and Python interface
  command scripts are now highlighted by default.  Loading all syntax
  files incurs an undesirable load-time burden so highlighting of the
  less popular MzScheme, Perl, Ruby and Tcl interfaces is disabled by
  default.  g:vimsyn_embed can still be used to customise the supported
  interfaces.
- Always highlight interface ex-commands as valid commands, even when
  the corresponding command-script highlighting is disabled.
- Highlight simple command-script statements as well as heredocs.
- Remove error highlighting of heredoc and statement command-script
  regions when an interface is disabled.  These are now highlighted as
  plain text.
- Allow indented heredoc end tokens when "trim" is specified.
- Match interface heredocs in :def functions.
- Fix runaway vimEmbedError regions.  These regions have been removed.
- Use python2 syntax for :python, and :pythonx when 'pyxversion' is
  appropriately set.

closes: #15522

Signed-off-by: Doug Kearns <dougkearns@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/syntax/generator/gen_syntax_vim.vim

@@ -1,7 +1,7 @@
 " Vim syntax file generator
-" Language: Vim script
-" Maintainer: Hirohito Higashi (h_east)
-" Last Change: 2025 Apr 27
+" Language:		 Vim script
+" Maintainer:  Hirohito Higashi (h_east)
+" Last Change: 2025 May 16
 
 let s:keepcpo= &cpo
 set cpo&vim
@@ -301,14 +301,32 @@ function s:get_vim_command_type(cmd_name)
 		lvimgrep
 		lvimgrepadd
 		make
+		lua
+		luado
+		luafile
 		map
 		mapclear
 		match
+		mzscheme
+		mzfile
 		noremap
 		new
 		normal
+		perl
+		perldo
 		popup
 		public
+		python
+		pyfile
+		pydo
+		python3
+		py3
+		py3do
+		py3file
+		pythonx
+		pyx
+		pyxdo
+		pyxfile
 		redir
 		return
 		set
@@ -321,6 +339,9 @@ function s:get_vim_command_type(cmd_name)
 		static
 		substitute
 		syntax
+		tcl
+		tcldo
+		tclfile
 		this
 		throw
 		type