Create an agent editor page

Proposal

In the AI catalog, we want a way to edit and create agents. Create a route at /explore/ai-catalog/agents/:agent-id that allows you to edit the agent with the appropriate id.

Right now, we don't have the data needed for this so we'll need to mock it. We'll need to edit the following fields to start with (See this discussion for more details):

interface AIAgent {
  identifier: string(255); 
  name: string(255);
  description: string(1024);
  systemPrompt: string(1,000,000);
  userPrompt: string(1,000,000);
}

Use GitLab UI and follow standard GitLab design principals to get something running quickly. The focus here is on shipping something that we can iterate on. Here's a screenshot of what that could look like: