Add DocumentationTests to tests.py:

* test_tutorial runs doc/tutorial.rst as a doctest.
* test_commandline runs the "$ " shell sessions of the bash code blocks
  in doc/commandline.rst against the CLI of this checkout and compares
  stdout with the documented output. "$ cat FILE" provides the example
  input files.

The new tests uncovered several broken examples, which are fixed:

* tutorial: multi-line statements lacked "..." continuation prompts,
  from_string() was called with a placeholder string, results were shown
  for assignments, and the result of from_string() was discarded.
* commandline: jsondiff output used an outdated operation order and key
  order, jsondiff prints nothing (not "[]") for equal files, and the
  usage texts were outdated.

simplejson is added to the dev requirements for the tutorial examples, and
the doc sources are shipped in the sdist, which already includes tests.py.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PewzpkVb4tA4eWEkCzH9vT

Raise JsonPatchConflict when removing from immutable containers

…-application

docs: explain copy and in-place behavior when a patch fails