binman: Add support for building a binmanu PyPi package

Create the necessary files to build this new package.

It is not actually clear whether this is useful, since buildman has no
purpose outside U-Boot.

Move the main program into a function so that it can easily be called by
the PyPi-created script.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/pyproject.toml b/tools/binman/pyproject.toml
new file mode 100644
index 0000000..b4b54fb
--- /dev/null
+++ b/tools/binman/pyproject.toml
@@ -0,0 +1,29 @@
+[build-system]
+requires = ["setuptools>=61.0"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "binary-manager"
+version = "0.0.2"
+authors = [
+  { name="Simon Glass", email="sjg@chromium.org" },
+]
+dependencies = ["pylibfdt", "u_boot_pylib", "dtoc"]
+description = "Binman firmware-packaging tool"
+readme = "README.rst"
+requires-python = ">=3.7"
+classifiers = [
+    "Programming Language :: Python :: 3",
+    "License :: OSI Approved :: GNU General Public License v2 or later (GPLv2+)",
+    "Operating System :: OS Independent",
+]
+
+[project.urls]
+"Homepage" = "https://u-boot.readthedocs.io/en/latest/develop/package/index.html"
+"Bug Tracker" = "https://source.denx.de/groups/u-boot/-/issues"
+
+[project.scripts]
+binman = "binman.main:start_binman"
+
+[tool.setuptools.package-data]
+patman = ["*.rst"]