fix: fixing empty IDF_PATH for offline online installer (#1101)

Author: sigmaaa

bundles/com.espressif.idf.ui/src/com/espressif/idf/ui/tools/ToolsActivationJob.java

@@ -199,6 +199,7 @@ private void setEnvVarsInEclipse()
 		});
 		String path = replacePathVariable(idfToolSet.getEnvVars().get(IDFEnvironmentVariables.PATH));
 
+		idfEnvironmentVariables.addEnvVariable(IDFEnvironmentVariables.IDF_PATH, idfToolSet.getIdfLocation());
 		idfEnvironmentVariables.addEnvVariable(IDFEnvironmentVariables.PATH, path);
 		idfEnvironmentVariables.addEnvVariable(IDFEnvironmentVariables.PYTHON_EXE_PATH,
 				idfToolSet.getSystemPythonExecutablePath());