Add globalAPI option to expose the editor API through a global monaco object

[sangmokh]

What

• This PR intends to resolve the issue of not being able to set globalAPI: true on MonacoEnvironment when using monaco-editor-webpack-plugin due to the fact that MonacoEnvironment is specified inside the webpack plugin.
• Since 0.22.0 version of monaco-editor, the ESM version of the editor does no longer define a global monaco object unless global.MonacoEnvironment = { globalAPI: true } is set (change log).
• Issue link: Unable to use global.MonacoEnvironment = { globalAPI: true } to define a global monaco object #146

How

• Add globalAPI option (boolean) to specify whether the editor API should be exposed through a global monaco object or not. It defaults to false to preserve the current behavior of the webpack plugin.

[ghost]

All CLA requirements met.

[alexdima]

Thank you, looks great!