fix #10127
fix #5972

Forcing insert-mode after the first paste-chunk seems to work, as an
alternative to a9e2bae0eb69 (insert-before-cursor).

NB: Dot-repeat needs to match the original action.  Since a9e2bae0eb69
changed paste to insert-before-cursor, dot-repeat must also. But that
makes dot-repeat unpleasant/unusual.

Inserting "after" the cursor in Normal-mode, for big paste-streams, is
not reliable: sometimes the text "after" the cursor ends up in the
middle of the pasted text.  Maybe the cursor position is not updated?

To avoid weird behavior, always paste "before".  Maybe nvim_put() or
vim.paste() can be fixed more properly later.

Problem:  If multiple paste "chunks" are streamed, chunks after the
          first line are pasted into the buffer.
Solution: Check for cmdline-mode for all chunks in a paste-stream.

- Workaround #10966: 'paste' option is not always reset.
- In any case there's not much reason to wait until phase=3, because
  pasting in cmdline-mode skips lines after the first line (thus the
  `:set paste .. :set nopaste` dance happens only ~once).

Attempt to fix test failure since 976c6667e140 removed per-chunk redraw:

  ERROR test/functional/terminal/tui_spec.lua: TUI paste: cmdline-mode inserts 1 line
  test/functional/terminal/tui_spec.lua:367: in function <test/functional/terminal/tui_spec.lua:360
  Expected:
    |*foo                                               |
    |*                                                  |
    |{4:~                                                 }|
    |{4:~                                                 }|
    |{5:[No Name] [+]                                     }|
    |:"line 1{1:"}                                         |
    |{3:-- TERMINAL --}                                    |
  Actual:
    |*                                                  |
    |*{4:~                                                 }|
    |{4:~                                                 }|
    |{4:~                                                 }|
    |{5:[No Name] [+]                                     }|
    |:"line 1{1:"}                                         |
    |{3:-- TERMINAL --}                                    |