The commit:
1. use static property to configure a builder option
2. introduce the concept of dependencies to access the plugin's shared
   in builder option
3. make a plugin context the same for Plugin, BuilderOption and
   BuilderAction to have the same API in each class.

Before this commit, to define an option, we had to define a javascript
object that would contain the information of the option within the
`builder_options` resource.

```js
class MyPlugin extends Plugin {
    resources: {
        builder_options: [
        {
            selector: "div.selector",
            template: "my.owlTemplate",
            cleanForSave() {}
            // ... other option props
        }
        ]
    }
}

// For a custom component
class MyPlugin extends Plugin {
    resources: {
        builder_options: [
        {
            selector: "div.selector",
            template: MyCustomComponent,
            cleanForSave() {}
            // ... other option props
        }
        ]
    }
}

class MyCustomComponent extends BaseOptionComponent {
    // ...
}
```

When building anything for the builder, there is 3 classes that are
important: `Plugin`, `BaseOptionComponent`, `BuilderAction`.

In practice, the option object defined in builder_options feels
strange. On the other hand, making the configuration of the option as
a static property of the component somehow feels simpler as everything
related to that option is defined in the same class.

```js
class MyPlugin extends Plugin {
  resources: {
    builder_options: [MyCustomComponent]
  }
}

class MyCustomComponent extends BaseOptionComponent {
  static template = "my.owlTemplate";
  static selector = "div.selector";
  static cleanForSave(context) {}
  // ...
}
```

To have the same mental context in the 3 important class, they all
share the same API (`dependencies`, `dispatchTo`, `getResource`, ...)
(see `Editor.getPluginContext`)

To access a plugin shared method, it's now the same for `Plugin`,
`BuliderAction` and `BaseOptionComponent`:

```js
class MyCustomComponent extends BaseOptionComponent {
    static selector = "mySelector";
    static dependency = "myPlugin";
    myMethod() {
        this.dependencies.myPlugin.pluginMethod();
    }
}
```

To access a resource, dispatch, ...:

```js
class MyCustomComponent extends BaseOptionComponent {
    static selector = "mySelector";
    myMethod() {
        const resource = this.getResource('myResource');
    }
}
```