Include dist-info for python3-dnf

This is the DNF 4 cousin to this patch [0] for DNF 5.

Per [1], Python packages should include some minimal distribution
metadata, e.g. to make the package appear in `pip list`.

Perhaps the "proper way" to generate this dist-info metadata would be to
write a pyproject.toml and use a conventional Python build system like
Poetry to build `python3-dnf` rather than doing it with CMake, but this
is a way to do it with minimal changes to the build process.

Closes RhBug:2239323 [2]

[0] rpm-software-management/dnf5#447
[1] https://packaging.python.org/en/latest/specifications/core-metadata/#core-metadata,
[2] https://bugzilla.redhat.com/show_bug.cgi?id=2239323

= changelog =
msg: Add metadata for `dnf` Python package
type: bugfix
resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2239323

dnf.spec

@@ -363,6 +363,7 @@ popd
 %{_bindir}/%{name}-3
 %{_bindir}/%{name}4
 %exclude %{python3_sitelib}/%{name}/automatic
+%{python3_sitelib}/%{name}-*.dist-info
 %{python3_sitelib}/%{name}/
 %dir %{py3pluginpath}
 %dir %{py3pluginpath}/__pycache__

dnf/CMakeLists.txt

@@ -3,6 +3,15 @@ INSTALL (FILES ${dnf_SRCS} DESTINATION ${PYTHON_INSTALL_DIR}/dnf)
 # const.py is generated so the glob alone won't see it:
 INSTALL (FILES const.py DESTINATION ${PYTHON_INSTALL_DIR}/dnf)
 
+# Generate dist-info metadata
+SET(DISTINFO_PATH "${CMAKE_CURRENT_BINARY_DIR}/dnf-${DNF_VERSION}.dist-info")
+SET(METADATA_FILE "${DISTINFO_PATH}/METADATA")
+FILE(MAKE_DIRECTORY ${DISTINFO_PATH})
+FILE(WRITE ${METADATA_FILE} "Metadata-Version: 2.1\n")
+FILE(APPEND ${METADATA_FILE} "Name: dnf\n")
+FILE(APPEND ${METADATA_FILE} "Version: ${DNF_VERSION}\n")
+INSTALL(DIRECTORY ${DISTINFO_PATH} DESTINATION ${PYTHON_INSTALL_DIR})
+
 ADD_SUBDIRECTORY (automatic)
 ADD_SUBDIRECTORY (cli)
 ADD_SUBDIRECTORY (conf)