fix: increase code suggestions icon size

Description

1. Increases the size of the code suggestions icon, by providing an SVG that matches the bounding box.
2. Fixes the blocked-in loading and error bubbles.

The previous SVGs were 22px, the new ones are 14px with no spacing around the edges. This allows the SVG to properly fill the 14px bounding box.

Note - these icons diverge from those used in the shared dependency, which will cause an optional CI job to fail. We will either bring the svg repo in line, after verifying that this update works in the other dependencies (Visual Studio, and JetBrains?) or leave them as-is. Either way, we should be ok to merge this first and get the fix released, before doing any repo tidy-up.

Related Issues

Part of #765 (closed)

How has this been tested?

1. Check out this branch.
2. Enable code suggestions and the language server in settings.json, restarting if necessary:

   {
     "gitlab.featureFlags.languageServer": true,
     "gitlab.aiAssistedCodeSuggestions.enabled": true
   }

3. Run the extension host.
4. Observe the state of the gitlab icon in the status bar while performing various actions, e.g. typing or disabling code suggestions.

Screenshots (if appropriate):

Notice the status icon in the bottom bar:

state	before	after
enabled
disabled
loading
error

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation
• Chore (Related to CI or Packaging to platforms)
• Test gap