fix: adding page size param to highlights

[kiram15]

Adding customization to the page_size so that we can increase it to 12 (to fetch all in one page), since 12 is the limit of highlights one customer can add.

Jira link

Post-review

• Squash commits into discrete sets of changes
• Ensure that once the changes have been deployed to stage, prod is manually deployed

[adamstankiewicz]

[inform/suggestion] While PageNumberWithSizePagination is the pagination_class mostly used throughout this app, there is an opportunity to rely on DefaultPagination from edx-drf-extensions (source) which is a more standard, out-of-the-box pagination_class within Open edX that includes the same page_size as PageNumberWithSizePagination but with a more consistent serialized pagination response compared to the default PageNumberPagination or the custom PageNumberWithSizePagination class.

from edx_rest_framework_extensions.paginators import DefaultPagination

pagination_class = DefaultPagination

Relying on DefaultPagination here and throughout the IDA would effectively eliminate the need for the custom PageNumberWithSizePagination paginator class altogether.

[adamstankiewicz]

Related, I also might wonder if we should start ensuring the default pagination class in the base REST_FRAMEWORK settings (source) for our Enterprise IDAs is set to DefaultPagination so all APIs use it by default without needing to explicitly opt-in to it.

# Django Rest Framework
REST_FRAMEWORK = {
    'DEFAULT_PAGINATION_CLASS': 'edx_rest_framework_extensions.paginators.DefaultPagination',
}