vim-patch:partial:9.1.0027: Vim is missing a foreach() func (#27037)

Problem:  Vim is missing a foreach() func
Solution: Implement foreach({expr1}, {expr2}) function,
          which applies {expr2} for each item in {expr1}
          without changing it (Ernie Rael)

closes: vim/vim#12166

e79e207760

Partial port as this doesn't handle non-materialized range() lists.

vim-patch:c92b8bed1fa6

runtime(help): delete duplicate help tag E741 (vim/vim#13861)

c92b8bed1f

Co-authored-by: Ernie Rael <errael@raelity.com>

src/nvim/eval.lua

@@ -2923,6 +2923,48 @@ M.funcs = {
     returns = 'string',
     signature = 'foldtextresult({lnum})',
   },
+  foreach = {
+    args = 2,
+    base = 1,
+    desc = [=[
+      {expr1} must be a |List|, |String|, |Blob| or |Dictionary|.
+      For each item in {expr1} execute {expr2}. {expr1} is not
+      modified; its values may be, as with |:lockvar| 1. |E741|
+      See |map()| and |filter()| to modify {expr1}.
+
+      {expr2} must be a |string| or |Funcref|.
+
+      If {expr2} is a |string|, inside {expr2} |v:val| has the value
+      of the current item.  For a |Dictionary| |v:key| has the key
+      of the current item and for a |List| |v:key| has the index of
+      the current item.  For a |Blob| |v:key| has the index of the
+      current byte. For a |String| |v:key| has the index of the
+      current character.
+      Examples: >
+      	call foreach(mylist, 'let used[v:val] = v:true')
+      <This records the items that are in the {expr1} list.
+
+      Note that {expr2} is the result of expression and is then used
+      as a command.  Often it is good to use a |literal-string| to
+      avoid having to double backslashes.
+
+      If {expr2} is a |Funcref| it must take two arguments:
+      	1. the key or the index of the current item.
+      	2. the value of the current item.
+      With a lambda you don't get an error if it only accepts one
+      argument.
+      If the function returns a value, it is ignored.
+
+      Returns {expr1} in all cases.
+      When an error is encountered while executing {expr2} no
+      further items in {expr1} are processed.
+      When {expr2} is a Funcref errors inside a function are ignored,
+      unless it was defined with the "abort" flag.
+    ]=],
+    name = 'foreach',
+    params = { { 'expr1', 'any' }, { 'expr2', 'any' } },
+    signature = 'foreach({expr1}, {expr2})',
+  },
   foreground = {
     args = 0,
     params = {},