CI/CD: Implement weekly builds.

Brings over the functionality in https://github.com/FreeCAD/FreeCAD-Bundle
to build Linux AppImage, macOS .dmg, and Windows 7z releases.

This version also creates a tagged release for each build, creating an
archive of the weekly builds as well as the ability to easily tie each
build to a git commit.  This will make running 'git bisect' easy to
identify sources of regressions.

package/rattler-build/scripts/get_freecad_version.py

@@ -0,0 +1,53 @@
+import sys
+import os
+import subprocess
+import platform
+from datetime import datetime
+
+import freecad
+import FreeCAD
+
+package_manager = "conda"
+system = platform.platform().split("-")[0]
+arch = platform.machine()
+
+# Windows uses a different syntax
+if arch == "AMD64":
+    arch = "x86_64"
+
+if "ARCH" in os.environ:
+    if os.environ["ARCH"] != "":
+        arch = os.environ["ARCH"]
+
+python_version = platform.python_version().split(".")
+python_version = "py" + python_version[0] + python_version[1]
+date = str(datetime.now()).split(" ")[0]
+
+version_info = FreeCAD.Version()
+build_version_suffix = FreeCAD.ConfigGet("BuildVersionSuffix")
+dev_version = version_info[0] + "." + version_info[1] + "." + version_info[2] + build_version_suffix
+revision = version_info[3].split(" ")[0]
+
+if system == "macOS":
+    import jinja2
+    print("create plist from template")
+    osx_directory = os.path.join(os.path.dirname(__file__), "..", "osx")
+    with open(os.path.join(osx_directory, "Info.plist.template")) as template_file:
+        template_str = template_file.read()
+    template = jinja2.Template(template_str)
+    rendered_str = template.render( FREECAD_VERSION="{}-{}".format(dev_version, revision), 
+                                    APPLICATION_MENU_NAME="FreeCAD-{}-{}".format(dev_version, revision) )
+    with open(os.path.join(osx_directory, "FreeCAD.app", "Contents", "Info.plist"), "w") as rendered_file:
+        rendered_file.write(rendered_str)
+
+if "DEPLOY_RELEASE" in os.environ and os.environ["DEPLOY_RELEASE"] == "weekly-builds":
+    dev_version = "weekly-builds"
+    revision_separator = "-"
+else:
+    revision_separator = ""
+    revision = ""
+
+bundle_name = f"FreeCAD_{dev_version}{revision_separator}{revision}-{package_manager}-{system}-{arch}-{python_version}"
+
+with open("bundle_name.txt", "w") as bundle_name_file:
+    bundle_name_file.write(bundle_name)