Add support for generating compile_commands.json

- Integrate premake-ecc module for generating compile_commands.json
- Add .clangd config pointing to build/ directory
- Add 'Generate compile_commands.json' task
- Run compile_commands generation automatically on build

build/ecc/_manifest.lua

@@ -0,0 +1,4 @@
+return {
+	"_preload.lua",
+	"ecc.lua"
+}