implement /packages/{name} as its own route

A few things added with this commit:

- aurweb.packages.util
    - A module providing package and pkgbase helpers.
- aurweb.template.register_filter
    - A decorator that can be used to register a filter:
      @register_filter("some_filter") def f(): pass

Additionally, template partials have been split off a bit
differently. Changes:

- /packages/{name} is defined in packages/show.html.
- partials/packages/package_actions.html is now
  partials/packages/actions.html.
- partials/packages/details.html has been added.
- partials/packages/comments.html has been added.
- partials/packages/comment.html has been added.
- models.dependency_type additions: name and id constants.
- models.relation_type additions: name and id constants.
- models.official_provider additions: base official url constant.

Signed-off-by: Kevin Morris <kevr@0cost.org>

aurweb/templates.py

@@ -1,9 +1,11 @@
 import copy
+import functools
 import os
 import zoneinfo
 
 from datetime import datetime
 from http import HTTPStatus
+from typing import Callable
 from urllib.parse import quote_plus
 
 import jinja2
@@ -40,6 +42,31 @@ env.filters["captcha_cmdline"] = captcha.captcha_cmdline_filter
 env.filters["account_url"] = util.account_url
 
 
+def register_filter(name: str) -> Callable:
+    """ A decorator that can be used to register a filter.
+
+    Example
+        @register_filter("some_filter")
+        def some_filter(some_value: str) -> str:
+            return some_value.replace("-", "_")
+
+    Jinja2
+        {{ 'blah-blah' | some_filter }}
+
+    :param name: Filter name
+    :return: Callable used for filter
+    """
+    def decorator(func):
+        @functools.wraps(func)
+        def wrapper(*args, **kwargs):
+            return func(*args, **kwargs)
+        if name in env.filters:
+            raise KeyError(f"Jinja already has a filter named '{name}'")
+        env.filters[name] = wrapper
+        return wrapper
+    return decorator
+
+
 def make_context(request: Request, title: str, next: str = None):
     """ Create a context for a jinja2 TemplateResponse. """