Replace ./ import by @lib/ using Babel resolver

[tschaffter]

This PR aims to fix #27.

This PR replaces all relative import by absolute imports using @lib/.

npm run build and npm run test completes successfully.

[jb-adams]

i'm happy to do a review of this if you'd like

[tschaffter]

In #50, @jaeddy says:

The @lib/environment import apparently gets interpreted (when trying to use babel-node to compile and execute an ES6+ formatted script) as a module/dependency:

Currently we have in webpack.config.js:

    resolve: {
        alias: {
            '@lib': path.resolve(__dirname, 'src/lib')
        },
        extensions: ['.js'],
        modules: ['node_modules']
    },

First, I think that it is confusing to use the prefix "@" for aliases since this is also the prefix for npmjs organization like "@sentinel-one/ui-compodoc".

Second, we are currently using webpack to define the alias. In #50, @jaeddy proposes to use the Babel plugin "babel-plugin-module-resolver". At the same time, I think that @jb-adams implemented the current solution that uses webpack aliases. The article shared by @jaeddy in #50 comment on this:

Aside: Alternative by using webpack
For completeness, you can probably also use webpack to achieve this; it has a resolve.alias configuration option which allows for similar behaviour and has a corresponding eslint resolver plugin available. Generally I shy away from a webpack solution when a babel solution is viable, since many more projects and tools use babel (either standalone or with webpack). The part where the webpack version shines is when you need to hijack entire modules in your build (e.g. mapping third party dependency react to inferno). Things like this are typically not done with babel since babel is rarely configured to run on things inside the node_modules folder.

We currently do not depend on the advantage mentioned by the author for the webpack solution. However, I think that there is an advantage to use the babel plugin approach: enabling developers to import gh-openapi-docs into their projects.

Proposal:

• Use another prefix character for aliases, for example "#" as used in Why You Should Use Babel Resolvers. We could also decide to drop the prefix character as illustrated in the README of the plugin babel-plugin-module-resolver.
• If at least one person agrees and there is no objection, I'll update the code to set the alias with babel instead of webpack.

[jb-adams]

• Use another prefix character for aliases, for example "#" as used in Why You Should Use Babel Resolvers. We could also decide to drop the prefix character as illustrated in the README of the plugin babel-plugin-module-resolver.
• If at least one person agrees and there is no objection, I'll update the code to set the alias with babel instead of webpack.

Sounds good to me. I wasn't aware that babel resolvers could do this (was only familiar with webpack resolvers).

+1 for using babel instead of webpack