python-installer: Add host-only package

From the README:

This is a low-level library for installing a Python package from a wheel
distribution. It provides basic functionality and abstractions for
handling wheels and installing packages from wheels.

Signed-off-by: Jeffery To <jeffery.to@gmail.com>
(cherry picked from commit 37caea7c93)

lang/python/python-installer/Makefile

@@ -0,0 +1,53 @@
+#
+# Copyright (C) 2023 Jeffery To
+#
+# This is free software, licensed under the GNU General Public License v2.
+# See /LICENSE for more information.
+#
+
+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=python-installer
+PKG_VERSION:=0.7.0
+PKG_RELEASE:=1
+
+PYPI_NAME:=installer
+PKG_HASH:=a26d3e3116289bb08216e0d0f7d925fcef0b0194eedfa0c944bcaaa106c4b631
+
+PKG_LICENSE:=MIT
+PKG_LICENSE_FILES:=LICENSE
+PKG_MAINTAINER:=Jeffery To <jeffery.to@gmail.com>
+
+PKG_HOST_ONLY:=1
+HOST_BUILD_DEPENDS:=python3/host python-flit-core/host
+
+PYTHON3_HOST_INSTALL_VARS:=PYTHONPATH=src
+
+include ../pypi.mk
+include $(INCLUDE_DIR)/package.mk
+include $(INCLUDE_DIR)/host-build.mk
+include ../python3-package.mk
+include ../python3-host-build.mk
+
+define Package/python3-installer
+  SECTION:=lang
+  CATEGORY:=Languages
+  SUBMENU:=Python
+  TITLE:=A library for installing Python wheels
+  URL:=https://github.com/pypa/installer
+  DEPENDS:=+python3-light +python3-email
+  BUILDONLY:=1
+endef
+
+define Package/python3-installer/description
+This is a low-level library for installing a Python package from a wheel
+distribution. It provides basic functionality and abstractions for
+handling wheels and installing packages from wheels.
+endef
+
+Host/Compile=$(Py3Host/Compile/Bootstrap)
+
+$(eval $(call Py3Package,python3-installer))
+$(eval $(call BuildPackage,python3-installer))
+$(eval $(call BuildPackage,python3-installer-src))
+$(eval $(call HostBuild))