Expose kintone-plugin-packer/from-manifest

[koba04]

When I use the Node API of kintone-plugin-packer, I have to create a buffer of a zipped contents.
In order to create the buffer, I have to implement a feature that is implemented in kintone-plugin-packer, which is a creating the buffer based on the manifest.json.

I think it would be nice if kintone-plugin-packer had an API to create a plugin from a path of a manifest.json.
This PR is to expose the API.

const packPluginFromManifest = require('kintone-plugin-packer/from-manifest');
packPluginFromManifest('path/to/manifest.json', privateKey).then(output => {
  console.log(output.id);
  fs.writeFileSync('./private.ppk', output.privateKey);
  fs.writeFileSync('./plugin.zip', output.plugin);
});

It's fine for me to expose createContentsZip but it seems to not be useful for others except me. :)

[teppeis]

@koba04 thanks! but it is not an formal API and may be implicitly changed or deleted in the future.

[koba04]

@teppeis Thanks! Yes, it's not an ideal API interface. we should revamp the API to support more use-cases.

[teppeis]

@koba04 released in v0.8.0!