Show loading feedback while Comment and Resolve is resolving a thread #9155

Follow-up from verifying #3568.

• Extension version: 0.175.2026110204
• VSCode Version: 1.145.0-insider (67710841ad061a9e253214f87bf5415a185ab2ff, arm64)
• OS: macOS
• Repository Clone Configuration (single repository/fork of an upstream repository): Single repository
• GitHub Product (GitHub.com/GitHub Enterprise version x.x.x): GitHub.com

Steps to Reproduce:

1. Open a pull request in VS Code Insiders with an unresolved inline review thread.
2. Enter a reply and click Comment and Resolve.
3. Observe the thread while the action completes.

Actual behavior:

The new comment appears in the UI immediately. About a second later, the thread resolves and disappears. There is no apparent loading feedback during that interval. Because the comment has already appeared but the thread remains unresolved, the action briefly feels broken or only partially completed.

Expected behavior:

Show a visible loading/progress indication until both posting the comment and resolving the thread have completed, so it is clear that the combined action is still in progress.

The combined action did ultimately post the reply and resolve the thread; this follow-up concerns feedback during the intermediate state, not a failure of the feature requested in #3568.