Store configuration used to initialize the project on a TWA Manifest on a file

[andreban]

Currently, llama-pack uses a Web Manifest to extract data, asks the user to confirm the values and generates build.gradle and app/AndroidManifest from it.

This would introduce an intermediate configuration file, with a format similar to Web Manifest.

The configuration will be used when applying updates to the template project to an existing project, as described on #3.

Developers can also use it to tweak configurations for their project an re-generate the project from it.

@FluorescentHallucinogen FYI

[andreban]

Closed by #29