Adding support for custom plugin import

[teresaqhoang]

Motivation and Context

This PR adds support for custom plugins. This implementation follows manifest requirements set by OpenAI for custom ChatGPT plugins and is defined here: https://learn.microsoft.com/en-us/semantic-kernel/ai-orchestration/chatgpt-plugins#add-the-plugin-manifest-file

Description

webapi

• Added GetPluginAuthHeaders() to ChatController.cs to parse plugin auth values from request headers. This was manually parsed using hardcoded headers before.
  • Standardized all plugin headers to x-sk-copilot-(.*)-auth
• Updated RegisterPlannerSkillsAsync() to accept a Dictionary of auth headers and register authenticated skills with the planner's kernel.
• Added logic to register custom plugins from context variables, including support for loading custom plugins from manifest files with authentication support for user PAT and no auth.

webapp

• General
  • Added .well-known* to .gitignore.
  • Consolidated all hooks into libs/hooks directory. Updated imports accordingly
  • Consolidated dialog styles into shared class
• Create BaseCard component to render a generic card.
  • Add AddPluginCard component to render a card for adding custom plugins. Card action triggers Plugin Wizard
  • Create PluginCard component to render a card for existing plugins.
• Fix PluginGallery component to use new PluginCard and AddPluginCard components.
• Update PluginConnector component to use new Dialog classes.
• Remove unused code from PluginCard and PluginConnector components.
• Create PluginWizard component to handle custom plugin import. Includes three steps: EnterManifestStep, ValidateManifestStep, and a confirmation page
• Manifest Validation:
  • Domain is a valid URL (doesn't throw when constructed using new URL)
  • Meets all the property requirements as defined by OpenAI
• If manifest domain is valid and user imports plugin, a new card will be added for that plugin at the end of the plugin gallery. User must explicitly enable the plugin before it's used with the planner.
• If plugin is enabled, header matching x-sk-copilot-{pluginNameForModel}-auth is added to request for bot response.

New Plugin Gallery look with Import card

New card for custom plugin added to gallery

Plugin Wizard

• If URL is invalid:
  

Validate Manifest Step

• If Manifest validation fails:
  

Confirmation

Enabling custom Plugin

Once user enables plugin, sample request herader:

Planner integration

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines and the pre-submission formatting script raises no violations
  - [ ] All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄