feat: add bundle configuration

[alexpozzi]

This PR includes the bundle configuration parser and bootstraps the extension that will automatically create services based on the provided configuration.

The configuration allows to configure one or multiple backends with the following parameters:

snappy:
  backends:
    my_first_backend:
      driver: wkhtmltopdf
      binary_path: /usr/bin/wkhtmltopdf
      timeout: 30
      options:
        my_option_1: my_value_1
        my_option_2: my_value_2
    my_second_backend:
      driver: chromium
      binary_path: /usr/bin/chromium

The above configuration will expose two services named snappy.my_first_backend and snappy.my_second_backend plus (potentially) all their variations for inputs and outputs.

The available parameters are the following:

• driver: the backend to use, for the moment the supported options are wkhtmltopdf and chromium
• binary_path: the backend binary path
• timeout: the timeout in seconds
• options: a key/value pair of options

Users will also be able to configure multiple backends of the same type, with different configurations.

In case we will like to support other backends that are not binary based we will add another configuration type more suited to them.

Does that work for you?

Note: in this PR I also fixed the CI workflow.

[qroques]

What does it mean to use parenthesis around your commands?

[alexpozzi]

It means that it's scoped and the cd executed inside it does not affect following instructions.

[qroques]

ok then 👍