nes: feat: ghost-text-like behavior

[ulugbekna]

No description provided.

[Copilot]

Pull request overview

Adds an experiment-gated “ghost-text-like” behavior for NES by tracking whether a cached suggestion was previously rendered as inline (ghost text) and suppressing re-serving it in non-inline form.

Changes:

• Introduces a team-internal experiment setting to enable/disable the behavior gate.
• Threads a reference to the underlying NES cache entry through NextEditResult and records a wasRenderedAsInlineSuggestion flag.
• Suppresses non-inline re-show of previously-inline cached NES suggestions; adds a caching-focused regression test.

Show a summary per file

File	Description
extensions/copilot/src/platform/configuration/common/configurationService.ts	Adds experiment-based config key to control the “mimic ghost text behavior” gating.
extensions/copilot/src/extension/inlineEdits/vscode-node/inlineCompletionProvider.ts	Implements the suppression gate and marks cache entries when an inline completion is shown.
extensions/copilot/src/extension/inlineEdits/test/node/nextEditProviderCaching.spec.ts	Adds test coverage for exposing/persisting cache entry references and flags across cache lookups.
extensions/copilot/src/extension/inlineEdits/node/nextEditResult.ts	Extends NextEditResult to carry a cache entry reference for consumers.
extensions/copilot/src/extension/inlineEdits/node/nextEditProvider.ts	Plumbs cache entry references into NextEditResult for both cached and freshly-cached results.
extensions/copilot/src/extension/inlineEdits/node/nextEditCache.ts	Adds wasRenderedAsInlineSuggestion flag to cached edit entries.

Copilot's findings

• Files reviewed: 6/6 changed files
• Comments generated: 1