[6.1] Serve site modules in ModuleHelper when in API context

[itsnewtjam]

Summary of Changes

This change modifies ModuleHelper to process site modules when running in ApiApplication context. Currently the /content/articles/{id} Web Services endpoint prepares the article content (e.g. {loadmodule} tags), but since ModuleHelper filters by the Client ID, no modules are rendered under ApiApplication.

This is a very basic way to address this, open to going about it a different way if there are implications I didn't think of!

Testing Instructions

Retrieve an article with modules rendered (assuming article ID 1 uses a load module tag of some sort)
GET /api/index.php/v1/content/articles/1

• Expected: Returns article data with modules rendered in the article text

Actual result BEFORE applying this Pull Request

Despite the endpoint preparing article content, ModuleHelper filters modules by Client ID, so no modules are rendered under ApiApplication.

Expected result AFTER applying this Pull Request

ModuleHelper serves site modules when under ApiApplication, resulting in modules being rendered in article content.

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed

[muhme]

@itsnewtjam Thank you for your contribution 👍 Since 5.4.0 is already in feature freeze mode, this PR needs to be moved to 6.1-dev. If you could make the rebase yourself, that would be great. Otherwise, we can support it.