Add build github actions workflows for mac/windows/linux.

etc/ci/generate_workflow.py

@@ -0,0 +1,59 @@
+# Copyright 2021 The Servo Project Developers. See the COPYRIGHT
+# file at the top-level directory of this distribution.
+#
+# Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+# http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+# <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+# option. This file may not be copied, modified, or distributed
+# except according to those terms.
+
+import os.path
+import sys
+
+BASE = os.path.dirname(__file__.replace('\\', '/'))
+sys.path.insert(0, os.path.join(
+    BASE, "..", "..", "components", "style", "properties", "Mako-1.1.2-py2.py3-none-any.whl"
+))
+
+from mako import exceptions  # noqa
+from mako.lookup import TemplateLookup  # noqa
+from mako.template import Template  # noqa
+
+
+def abort(message):
+    print(message, file=sys.stderr)
+    sys.exit(1)
+
+
+def render(filename, **context):
+    try:
+        lookup = TemplateLookup(directories=[BASE],
+                                input_encoding="utf8",
+                                strict_undefined=True)
+        template = Template(open(os.path.join(BASE, filename), "rb").read(),
+                            filename=filename,
+                            input_encoding="utf8",
+                            lookup=lookup,
+                            strict_undefined=True)
+        # Uncomment to debug generated Python code:
+        # write("/tmp", "mako_%s.py" % os.path.basename(filename), template.code)
+        return template.render(**context)
+    except Exception:
+        # Uncomment to see a traceback in generated Python code:
+        # raise
+        abort(exceptions.text_error_template().render())
+
+
+def main():
+    with open(os.path.join(".github", "workflows", "main.yml"), 'w') as f:
+        f.write(render(
+            'workflow.mako',
+            total_chunks=20,
+            GITHUB_REPOSITORY="${{ github.repository }}",
+            GITHUB_REF="${{ github.ref }}",
+            GITHUB_SHA="${{ github.sha }}",
+        ))
+
+
+if __name__ == "__main__":
+    main()