In-Context HTTP Snippet generation

[sebastienlevert]

As part of the HTTP Snippet generation, we want to allow developers to generate HTTP snippets as they are browsing the API Explorer. We want them to be able to explorer but also test an API as they move along their discoverability journey.

• Developers needs to be able to select an endpoint and generate an http snippet in the current active http file. If not active http file, it should create a temporary file.
• When a developer is using a temporary file, at save time, it should ask the user to save it as part of their project
• When a developer is generating another http snippet, it should append it to the active http file.

@maisarissi can you work with design on getting the right interaction with API Explorer?