Notifies listeners that the given keys changed, the way VS Code reports a configuration change: fully qualified leaf keys, not section names.
The resulting affects(section) says yes when a changed key is that
section or sits under it — so _fireChange(['sample.projects.enabled'])
affects sample.projects, while a change to sample.pro does not.
Removes every configured value.
Writes a value into a specific tier.
Optionalplacement: FakeSettingsPlacementReturns every tier for a setting, or undefined for an unknown key.
Optionalscope: SettingsScopeSubscribes to configuration changes.
Reads the effective value, with VS Code's own tier resolution applied.
Optionalscope: SettingsScopeWrites a value to the requested tier. Passing undefined removes that
tier's value. Rejections from the platform propagate to the caller.
Optionalscope: SettingsScopeOptionaloverrideInLanguage: boolean
In-memory settings capability for tests.