chore: make CLI error message more descriptive (#32593)

Summary:
motivation: I have a custom setup and needed to provide `react.cliPath`. I mistakenly provided path to `react-native-community/cli` which resulted into JS bundle not being generated. This error message provides a little more detail.

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[General] [Changed] - Improved error message in react.gradle

Pull Request resolved: #32593

Test Plan: I guess it's not needed in this case

Reviewed By: ShikaSD

Differential Revision: D32427929

Pulled By: cortinico

fbshipit-source-id: 2be340a8be15c8ec08873c0368a36b449c8b5030

react.gradle

@@ -32,7 +32,7 @@ def detectCliPath(config) {
         return "${projectDir}/../../node_modules/react-native/cli.js"
     }
     throw new Exception("Couldn't determine CLI location. " +
-             "Please set `project.ext.react.cliPath` to the path of the react-native cli.js");
+             "Please set `project.ext.react.cliPath` to the path of the react-native cli.js file. This file typically resides in `node_modules/react-native/cli.js`");
 }
 
 def composeSourceMapsPath = config.composeSourceMapsPath ?: "node_modules/react-native/scripts/compose-source-maps.js"