In app notifications for Prompts and Prompt Library

[chenkc805]

Fulfills:

• https://linear.app/sourcegraph/issue/PROD-171/we-surface-this-importer-tool-in-the-vs-code-app
• https://linear.app/sourcegraph/issue/PROD-170/show-a-tooltip-that-notifies-the-user-commands-are-now-prompts-when

Does the following:

• Create a dialogue that notifies the user that Commands are now Prompts
• Adds a hyper link to the Prompt Library importer so users with Custom Commands can import their prompts

Still need to do:

• [ ] Polish the copy
• [ ] Update the "Import" hyperlink to the right link @sqs
• [ ] Update the "Learn more" hyperlink to the correct docs location
• [ ] Determine if Edit, Document, and Generate Unit Tests should not be in the "Prompts" drawer, since they're not technically Prompts.

Test plan

QA on local

Changelog