feat(fastapi): add configurable commit hash display

Two new options have been added:

- [devel] commit_url
    - URL including an %s format specifier that can be used to link
      to a webpage for the commit.
- [devel] commit_hash
    - HEAD's commit hash (produced via `git rev-parse HEAD`)

If a `[devel] commit_hash` is configured, a link to the commit based on
`[devel] commit_url` will be displayed in the aurweb footer in
the form: `HEAD@<commit_hash>`. If no `[devel] commit_url` is
configured, a non-linked hash will be displayed.

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

aurweb/testing/requests.py

@@ -20,9 +20,14 @@ class Client:
     host = "127.0.0.1"
 
 
+class URL:
+    path = "/"
+
+
 class Request:
     """ A fake Request object which mimics a FastAPI Request for tests. """
     client = Client()
     cookies = dict()
     headers = dict()
     user = User()
+    url = URL()