Add F4SE plugin template

Create a minimal Fallout 4 F4SE/CommonLibF4 starter repo with build, packaging, install, and rename scripts, plus initial plugin source, headers, and xmake configuration.

.editorconfig

@@ -0,0 +1,18 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = crlf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.{cpp,h,hpp}]
+indent_style = tab
+indent_size = 4
+
+[*.lua]
+indent_style = space
+indent_size = 4
+
+[*.md]
+trim_trailing_whitespace = false