refactor!: delete insertmode (#18547)

Neovim already removed `evim` (or any similar flags). The 'insertmode'
option is a weird remnant, so get rid of it.

The 'insertmode' option is replaced with a script that closely emulates
the option. This script is documented at :help 'insertmode'

1 files changed, 0 insertions, 24 deletions

diff --git a/test/functional/editor/mode_insert_spec.lua b/test/functional/editor/mode_insert_spec.lua
index 684dee69db..e3d3cdbd85 100644
--- a/test/functional/editor/mode_insert_spec.lua
+++ b/test/functional/editor/mode_insert_spec.lua
@@ -6,8 +6,6 @@ local expect = helpers.expect
 local command = helpers.command
 local eq = helpers.eq
 local eval = helpers.eval
-local meths = helpers.meths
-local poke_eventloop = helpers.poke_eventloop
 
 describe('insert-mode', function()
   before_each(function()
@@ -135,26 +133,4 @@ describe('insert-mode', function()
     feed('i<C-S-V><C-J><C-S-V><C-@><C-S-V><C-[><C-S-V><C-S-M><C-S-V><M-C-I><C-S-V><C-D-J><Esc>')
     expect('<C-J><C-@><C-[><C-S-M><M-C-I><C-D-J>')
   end)
-
-  describe([[With 'insertmode', Insert mode is not re-entered immediately after <C-L>]], function()
-    before_each(function()
-      command('set insertmode')
-      poke_eventloop()
-      eq({mode = 'i', blocking = false}, meths.get_mode())
-    end)
-
-    it('after calling :edit from <Cmd> mapping', function()
-      command('inoremap <C-B> <Cmd>edit Xfoo<CR>')
-      feed('<C-B><C-L>')
-      poke_eventloop()
-      eq({mode = 'n', blocking = false}, meths.get_mode())
-    end)
-
-    it('after calling :edit from RPC #16823', function()
-      command('edit Xfoo')
-      feed('<C-L>')
-      poke_eventloop()
-      eq({mode = 'n', blocking = false}, meths.get_mode())
-    end)
-  end)
 end)