Use existing content source for templates if one exists for project

[Michaelpalacce]

Description

Content Sources are a bit unique in Aria Automations Service Broker.

When creating a Content Source for a project that points to Cloud Templates in Assembler, then you are limited to exactly one content source. Attempting to create more leads to the attempt failing.

As such, the proposal is to use an already existing content source if one is present on the system.

There are 2 ways to achieve this:

1. Reactively - where the default will be used when a specific error is caught from the API.
2. Proactively - where we check if a content source already exists for Assembler Cloud Templates and use that instead.

NOTES:

• Only do this for Assembler Cloud Templates, not for other content sources.
• Log a warning

[Michaelpalacce]

This doesn't seem to be an issue... this currently works as expected and the correct CS is used