Add support for pyproject.toml and wsgi module paths

pip 23.1 removed the "setup.py install" fallback for projects that do
not have pyproject.toml and now uses a pyproject.toml which is vendored
in pip [1][2]. pip 24.2 has now deprecated a similar fallback to
"setup.py develop" and plans to fully remove this in pip 25.0 [3][4][5].
pbr supports editable installs since 6.0.0

pip 25.1 has now been released and the removal is complete.
by adding our own minimal pyproject.toml to ensure we are using the
correct build system.

This change also requires that we adapt how we generate our wsgi
entry point. when pyproject.toml is used the wsgi console script is
not generated in an editbale install such as is used in devstck

To adress this we need to refactor our usage of our wsgi applciation
to use a module path instead. This change does not remove
the declaration of our wsgi_scrtip entry point but it shoudl
be considered deprecated and it will be removed in the future.

To unblock the gate the devstack plugin is modifed to to deploy
using the wsgi module instead of the console script.

Finally supprot for the mod_wsgi wsgi mode is removed.
that was deprecated in devstack a few cycle ago and
support was removed in I8823e98809ed6b66c27dbcf21a00eea68ef403e8

[1] https://pip.pypa.io/en/stable/news/#v23-1
[2] https://github.com/pypa/pip/issues/8368
[3] https://pip.pypa.io/en/stable/news/#v24-2
[4] https://github.com/pypa/pip/issues/11457
[5] https://ichard26.github.io/blog/2024/08/whats-new-in-pip-24.2/
Closes-Bug: #2109608

Change-Id: Iad77939ab0403c5720c549f96edfc77d2b7d90ee

releasenotes/notes/add-wsgi-module-support-597f479e31979270.yaml

@@ -0,0 +1,30 @@
+---
+features:
+  - |
+    A new module, ``watcher.wsgi``, has been added as a place to gather WSGI
+    ``application`` objects. This is intended to ease deployment by providing
+    a consistent location for these objects. For example, if using uWSGI then
+    instead of:
+
+    .. code-block:: ini
+
+       [uwsgi]
+        wsgi-file = /bin/watcher-api-wsgi
+
+    You can now use:
+
+    .. code-block:: ini
+
+        [uwsgi]
+        module = watcher.wsgi.api:application
+
+    This also simplifies deployment with other WSGI servers that expect module
+    paths such as gunicorn.
+deprecations:
+  - |
+    The watcher-api-wsgi console script is deprecated for removal
+    in a future release. This artifact is generated using a setup-tools
+    extension that is provide by PBR which is also deprecated.
+    due to the changes in python packaging this custom extensions
+    is planned to be removed form all OpenStack projects in a future
+    PBR release in favor of module based wsgi applications entry points.

releasenotes/notes/bug-2103451-fixes-prometheus-queries-with-multiple-target-0e65d20711d1abe2.yaml

@@ -2,8 +2,7 @@
 fixes:
   - |
     When using prometheus datasource and more that one target has the same value
-    for the `fqdn_label`, the driver used the wrong instance label to query for host
-    metrics. The `instance` label is no longer used in the queries but the `fqdn_label`
+    for the ``fqdn_label``, the driver used the wrong instance label to query for host
+    metrics. The ``instance`` label is no longer used in the queries but the ``fqdn_label``
     which identifies all the metrics for a specific compute node.
-
-    .. _Bug 2103451: https://bugs.launchpad.net/watcher/+bug/2103451
+    see Bug 2103451: https://bugs.launchpad.net/watcher/+bug/2103451 for more info.