Get the new parts of the public API ready for publishing

[romaricpascal]

Brief

Wrap up the work on component initialisation (error callback for initAll, preventing double initialisation) and get a base component class in shape for publishing in our next release. This also includes making sure we've got the docs ready to go so we can tell people how to start using them.

Epic lead

@romaricpascal

Driving role(s)

@seaemsi, @patrickpatrickpatrick

Supporting roles

Needs awareness

Further detail

Component initialisation

Beta Give feedback

1. Add callback to respond to errors when a component does not initialise in initAll #5267
   +0
   
2. Investigate components being initialised more than once #1127
   javascript 🕔 hours +2
   
3. Update tests for onError callback to check usual logging does not happen #5303
   javascript +1
   
4. Make a base class for people to build components with part of our public API #5214
   javascript +1
5. [Stretch] Investigate configuration helpers
6. [Stretch] Investigate how to prevent component initialisation based on a condition #5225
   javascript +1
   

Docs

Beta Give feedback

1. Figure the best place for documentation to go in the existing docs govuk-frontend-docs#462
   documentation +1
2. Add documentation for isSupported to the Frontend docs
3. Add documentation for the updates to createAll and initAll to the Frontend docs
4. Add documentation for the base component class to the Frontend docs
5. Add documentation for the prevention of double initialisation
6. Add CHANGELOG entries for merged features #5321
   +0

Base component

Beta Give feedback

1. Add a isSupported @protected method to GOVUKFrontendComponent #5323
   +0
   
2. Refactor ElementError to use component's moduleName instead of componentName #5324
   +0
   
3. Refactor errors prefixed by the component name to use formatErrorMessage #5325
   +0
4. Rename $module to $root across the project #5322
   +0
5. Refactor the check for the type of the root element in GOVUKFrontendComponent #5326
   +0
6. Export GOVUKFrontendComponent publicly as Component #5327
   +0