feat(auth): use ctx.throw, add 40X responses to idp spec

[njlie]

Changes proposed in this pull request

• Adds 40X responses to the endpoints the AS extends for interactions
• Uses ctx.throw for all known errors.

Context

In order to surface certain errors properly, the needed to be reflected in the spec so that they wouldn't be swallowed by the validator.

Checklist

• Related issues linked using fixes #number
• Tests added/updated
• Documentation added
• Make sure that all checks pass

[wilsonianb]

Suggested change

	await expect(grantRoutes.create(ctx)).rejects.toHaveProperty(
	'status',
	400
	)
	await expect(grantRoutes.create(ctx)).rejects.toMatchObject({
	status: 400,
	error: 'interaction_required'
	})