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/models/package_dependency.py

@@ -61,3 +61,12 @@ class PackageDependency(Base):
         self.DepDesc = DepDesc
         self.DepCondition = DepCondition
         self.DepArch = DepArch
+
+    def is_package(self) -> bool:
+        from aurweb import db
+        from aurweb.models.official_provider import OfficialProvider
+        from aurweb.models.package import Package
+        pkg = db.query(Package, Package.Name == self.DepName)
+        official = db.query(OfficialProvider,
+                            OfficialProvider.Name == self.DepName)
+        return pkg.count() > 0 or official.count() > 0