Rework status reporting for codebase index (#4935)

* Rework status reporting for codebase index

For https://github.com/microsoft/vscode/issues/306229

Making a pass through the code to clean it up, make the wording more consistent, and handle states like https://github.com/microsoft/vscode/issues/306229

* Update src/extension/workspaceChunkSearch/vscode-node/workspaceIndexingStatus.ts

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update src/extension/workspaceChunkSearch/vscode-node/workspaceIndexingStatus.ts

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

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Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>