Introduce {% fill %} replacing 'fill' func of 'slot' tag

Partial implementation fill-tags plus update tests

Implement {% fill %} tags. Next: update tests.

Bring back support for {%slot%} blocks for bckwrd-compat and implement ambig. resolution policy

Update tests to use fill blocks. Add extra checks that raise errors

Add new tests for fill-slot nesting

Update README. Editing still required

remove unused var ctxt after flake8 complaint

fix flake8 warning about slotless f-string

[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Add new slot aliases in fill context. Clean up rendering logic in Component. Update docs.

fix flake8, isort, black errors

Refactor duplicated name validation

Add if_filled tag + elif_filled...else_filled...endif_filled for cond. slots

Fix mistake in do_if_filled() docstring

Upload templates for tests! D'oh

Incorporate PR feedback

Drop Literal type hint; Use isort off-on instead of skip in tests

Treat all fill,slot,if_filled,component names as variables

Reset sampleproject components

Add test for variable filled name

Update examples in docs

tests/django_test_setup.py

@@ -10,11 +10,12 @@ if not settings.configured:
                 "DIRS": ["tests/templates/"],
             }
         ],
-        COMPONENTS={"TEMPLATE_CACHE_SIZE": 128},
+        COMPONENTS={"template_cache_size": 128, "strict_slots": False},
         MIDDLEWARE=[
             "django_components.middleware.ComponentDependencyMiddleware"
         ],
         DATABASES={},
+        # DEBUG=True
     )
 
     django.setup()