fix(restart): append `-c <cmd>` at end, drop `-- [files…]` #37846

Problem:
- `:restart <cmd>` prepends `-c <cmd>` before the original `-c` args (if
  any). So the original `-c` args may "override" it, which is
  surprising.
- Confusing logic: `v:argv` is partially prepared in `ex_docmd.c`, and
  then later `ui.c` skips other parts of it.

Current behavior is nonsense, for example this sequence:

    :restart echo "Hello"
    :restart +qall echo "Hello" | echo "World"

results in this v:argv:

    [
      'nvim'
      '-c'
      'echo "Hello" | echo "World"'
      '--embed'
      '-c'
      'echo "Hello"'
      ...
    ]

Whereas after this commit, v:argv is:

    [
      'nvim'
      '--embed'
      ...
      '-c'
      'echo "Hello" | echo "World"'
    ]

Solution:
- Append `-c <cmd>` at the _end_ of `v:argv`, not the start.
- Use a dummy placeholder `+:::` to mark where the "restart command"
  appears in `v:argv`.
- Do all `v:argv` preparation in `ex_docmd.c`. This simplifies `ui.c`.
- Drop `-- [files…]` from `v:argv` since it is probably more annoying
  than useful. (Users can use sessions to restore files on restart.)

0 files changed, 0 insertions, 0 deletions