🎮Implement the functionality to create and edit blog posts

[OlenaYefymenko]

This PR:

• Adds new functions for the creation and edition of the posts;
• Integrates the tests;
• Provides updated templates and icons for the implementation of new functionality.

Link to task https://tutorial.djangogirls.org/en/django_forms/

Ref #18

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 100.00%. Comparing base (f6ccd09) to head (54f3d36).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #39 +/- ## ========================================== Coverage 100.00% 100.00% ========================================== Files 10 11 +1 Lines 118 222 +104 Branches 6 12 +6 ========================================== + Hits 118 222 +104 ```

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[OlenaYefymenko]

@webknjaz in this PR a lot of non-informative commits, I'll do a squash in the last push.

[OlenaYefymenko]

django-girls-blog-OlenaEfymenko on  18-12-django-forms-new-edit via 🐍 3.11.2 using ☁️  default/fertu-pipeline-dev via django-girls-blog-OlenaEfymenko took 2.2s 
➜ python -m coverage run manage.py test      
Traceback (most recent call last):
  File "/home/olenayefymenko/django-girls-blog-OlenaEfymenko/manage.py", line 73, in <module>
    main()
  File "/home/olenayefymenko/.pyenv/versions/3.11.2/lib/python3.11/contextlib.py", line 81, in inner
    return func(*args, **kwds)
           ^^^^^^^^^^^^^^^^^^^
  File "/home/olenayefymenko/django-girls-blog-OlenaEfymenko/manage.py", line 69, in main
    execute_from_command_line(sys.argv)
  File "/home/olenayefymenko/django-girls-blog-OlenaEfymenko/.venv/lib/python3.11/site-packages/django/core/management/__init__.py", line 442, in execute_from_command_line
    utility.execute()
  File "/home/olenayefymenko/django-girls-blog-OlenaEfymenko/.venv/lib/python3.11/site-packages/django/core/management/__init__.py", line 436, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/olenayefymenko/django-girls-blog-OlenaEfymenko/.venv/lib/python3.11/site-packages/django/core/management/__init__.py", line 275, in fetch_command
    klass = load_command_class(app_name, subcommand)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/olenayefymenko/django-girls-blog-OlenaEfymenko/.venv/lib/python3.11/site-packages/django/core/management/__init__.py", line 48, in load_command_class
    module = import_module("%s.management.commands.%s" % (app_name, name))
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/olenayefymenko/.pyenv/versions/3.11.2/lib/python3.11/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1206, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1178, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1149, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 940, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "/home/olenayefymenko/django-girls-blog-OlenaEfymenko/.venv/lib/python3.11/site-packages/django/core/management/commands/test.py", line 6, in <module>
    from django.test.runner import get_max_test_processes
  File "/home/olenayefymenko/django-girls-blog-OlenaEfymenko/.venv/lib/python3.11/site-packages/django/test/__init__.py", line 3, in <module>
    from django.test.client import AsyncClient, AsyncRequestFactory, Client, RequestFactory
  File "/home/olenayefymenko/django-girls-blog-OlenaEfymenko/.venv/lib/python3.11/site-packages/django/test/client.py", line 727
    session = await self.asession()
              ^^^^^^^^^^^^^^^^^^^^^
SyntaxError: 'await' outside async function
/home/olenayefymenko/django-girls-blog-OlenaEfymenko/.venv/lib/python3.11/site-packages/coverage/inorout.py:519: CoverageWarning: Module blog was previously imported, but not measured (module-not-measured)
  self.warn(msg, slug="module-not-measured")
/home/olenayefymenko/django-girls-blog-OlenaEfymenko/.venv/lib/python3.11/site-packages/coverage/inorout.py:519: CoverageWarning: Module mysite was previously imported, but not measured (module-not-measured)
  self.warn(msg, slug="module-not-measured")
/home/olenayefymenko/django-girls-blog-OlenaEfymenko/.venv/lib/python3.11/site-packages/coverage/control.py:887: CoverageWarning: No data was collected. (no-data-collected)
  self._warn("No data was collected.", slug="no-data-collected")

[OlenaYefymenko]

@webknjaz thank you for review, I'll change and push