API: nvim_put: always PUT_CURSEND

Fixes strange behavior where sometimes the buffer contents of a series
of paste chunks (vim._paste) would be out-of-order.

Now the tui_spec.lua screen-tests are much more reliable. But they still
sometimes fail because of off-by-one cursor (caused by "typeahead race"
resulting in wrong mode; fixed later in this patch-series).

src/nvim/api/vim.c

@@ -1249,13 +1249,7 @@ void nvim_put(ArrayOf(String) lines, String type, Boolean direction,
   finish_yankreg_from_object(reg, false);
 
   bool VIsual_was_active = VIsual_active;
-  int flags = 0;
+  int flags = PUT_CURSEND;
-  if (State & INSERT) {
-    flags |= PUT_CURSEND;
-  } else if (VIsual_active) {
-    // TODO: fix VIsual when cursor is before, or emulate the delete as well
-    flags |= lt(VIsual, curwin->w_cursor) ? PUT_CURSEND : 0;
-  }
   msg_silent++;  // Avoid "N more lines" message.
   do_put(0, reg, direction ? BACKWARD : FORWARD, 1, flags);
   msg_silent--;

test/functional/api/vim_spec.lua

@@ -382,6 +382,7 @@ describe('API', function()
         line 1
         line 2
         line 3]])
+      command('1')
       -- blockwise
       nvim('put', {'AA','BB'}, 'b', false)
       expect([[

test/functional/terminal/tui_spec.lua

@@ -190,9 +190,16 @@ describe('TUI', function()
   end)
 
   it('paste: exactly 64 bytes #10311', function()
+    local expected = string.rep('z', 64)
     -- "bracketed paste"
-    feed_data('i\027[200~'..string.rep('z', 64)..'\027[201~')
+    feed_data('i\027[200~'..expected..'\027[201~')
     feed_data(' end')
+    expected = expected..' end'
+    retry(nil, nil, function()
+      local _, buflines = child_session:request(
+        'nvim_buf_get_lines', 0, 0, -1, false)
+      eq({expected}, buflines)
+    end)
     screen:expect([[
       zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz|
       zzzzzzzzzzzzzz end{1: }                               |
@@ -210,9 +217,13 @@ describe('TUI', function()
     for i = 1, 3000 do
       t[i] = 'item ' .. tostring(i)
     end
-    local expected = table.concat(t, '\n')
     -- "bracketed paste"
-    feed_data('i\027[200~'..expected..'\027[201~')
+    feed_data('i\027[200~'..table.concat(t, '\n')..'\027[201~')
+    retry(nil, nil, function()
+      local _, buflines = child_session:request(
+        'nvim_buf_get_lines', 0, 0, -1, false)
+      eq(t, buflines)
+    end)
     feed_data(' end')
     screen:expect([[
       item 2997                                         |