Refactor ElementError class

[domoscargin]

What

Potential changes include:

• Ensuring ElementError.options.expectedType is always a string, when present
• Simplifying expected type error messages to something like ${identifier} is not of type ${expectedType || 'HTMLElement'}
• Make identifier the mandatory first param and move element into options:

constructor(identifier, {componentName, element, expectedType})

Why

Making expectedType a string allows us to avoid having different cases for when it's a string vs when it's an element, reducing our checks and allowing us to simplify the outputted message.

Using identifier as our mandatory param allows us to avoid the hack of passing in null as the element to get the right error messages.

Who needs to work on this

Developer

Who needs to review this

Developer

Done when

• A decision has been made on which changes to make
• Changes have been implemented
• All existing tests and throws have been refactored to work with the changes

[romaricpascal]

Little note to make sure we account for the Skip Link's error when there's no hash in the URL, which may need its own little case (see end of that comment on #4299).