[Stretch] Create a ConfigurableComponent class to further encapsulate receiving a configuration

[romaricpascal]

What

Create a GOVUKFrontendConfigurableComponent class that extends GOVUKFrontendComponent and encapsulate storing the configuration computed by getComponentConfiguration in this.config (similarly to how GOVUKFrontendComponent encapsulates storing the root of the component)

The constructor signature would be constructor(root, config).

Type wise, it’ll need to be a generic class, to allow components extending it to specify the type of the configuration object they work on: ConfigurableComponent<ConfigurationType, RootElementType> (configuration type first as it’s necessarily specified, while RootElementType is optional).

Update the components using getComponentConfiguration to use it.

Why

This would add further consistency to how components receive configuration, formalising the name of the variable storing the configuration and encapsulating a behaviour repeated by all components receiving configuration.

Who needs to work on this

Developers

Who needs to review this

Developers

Done when

• We added the GOVUKFrontendConfigurableComponent class
• We've updated our components to use it

[romaricpascal]

Closing as #5456 has been updated to implement a class rather than a function.