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/_preload.lua

@@ -0,0 +1,35 @@
+
+	local p = premake
+
+	newoption {
+		trigger = "config",
+		value = "CFG",
+		description = "Select config for export compile_commands.json"
+	}
+
+	newaction {
+		trigger         = "ecc",
+		shortname       = "Export compile commands",
+		description     = "Export compile_commands.json for language server",
+		toolset         = "gcc",
+
+		valid_kinds     = { "ConsoleApp", "WindowedApp", "StaticLib", "SharedLib" },
+		valid_languages = { "C", "C++" },
+		valid_tools     = {
+			cc     = { "clang", "gcc" }
+		},
+
+		onStart = function()
+			p.indent("  ")
+		end,
+
+		execute = function()
+			local dir = {}
+			dir.location = _MAIN_SCRIPT_DIR
+			p.generate(dir, "compile_commands.json", p.modules.ecc.generateFile)
+		end
+	}
+
+	return function(cfg)
+		return (_ACTION == "ecc")
+	end