feat(defaults): improve :grep defaults #28545

Based on feedback from #28324, pass -H and -I to regular grep
(available on all platforms officially supported by Neovim), and
only pass -uu to ripgrep. This makes :grep ignore binary files by
default in both cases.

src/nvim/options.lua

@@ -3382,7 +3382,7 @@ return {
       abbreviation = 'gp',
       defaults = {
         condition = 'MSWIN',
-        if_false = 'grep -n $* /dev/null',
+        if_false = 'grep -HIn $* /dev/null',
         if_true = 'findstr /n $* nul',
         doc = [[see below]],
       },
@@ -3392,10 +3392,7 @@ return {
         line.  The placeholder "$*" is allowed to specify where the arguments
         will be included.  Environment variables are expanded |:set_env|.  See
         |option-backslash| about including spaces and backslashes.
-        When your "grep" accepts the "-H" argument, use this to make ":grep"
-        also work well with a single file: >vim
-        	set grepprg=grep\ -nH
-        <	Special value: When 'grepprg' is set to "internal" the |:grep| command
+        Special value: When 'grepprg' is set to "internal" the |:grep| command
         works like |:vimgrep|, |:lgrep| like |:lvimgrep|, |:grepadd| like
         |:vimgrepadd| and |:lgrepadd| like |:lvimgrepadd|.
         See also the section |:make_makeprg|, since most of the comments there
@@ -3403,11 +3400,11 @@ return {
         This option cannot be set from a |modeline| or in the |sandbox|, for
         security reasons.
         This option defaults to:
-        - `rg --vimgrep -uuu $* ...` if ripgrep is available (|:checkhealth|),
-        - `grep -n $* /dev/null` on Unix,
+        - `rg --vimgrep -uu ` if ripgrep is available (|:checkhealth|),
+        - `grep -HIn $* /dev/null` on Unix,
         - `findstr /n $* nul` on Windows.
         Ripgrep can perform additional filtering such as using .gitignore rules
-        and skipping hidden or binary files. This is disabled by default (see the -u option)
+        and skipping hidden files. This is disabled by default (see the -u option)
         to more closely match the behaviour of standard grep.
         You can make ripgrep match Vim's case handling using the
         -i/--ignore-case and -S/--smart-case options.