feat: add dprint.showNoConfigNotification setting

[dsherret]

Formatting a file that has no dprint configuration file shows a "No dprint configuration file found" notification once per session. There was no way to turn it off, which is annoying when dprint is the default formatter and files outside a dprint project are opened regularly.

Changes

• New dprint.showNoConfigNotification setting (default true). When false, the notification isn't shown.
• The notification has a "Don't show again" button that sets the setting to false in the user settings.
• The setting is application scoped, so a workspace can't override it and make the button ineffective.
• The backend is no longer reinitialized for every dprint.* setting change, only for the settings it's initialized with (dprint.path, dprint.verbose, dprint.useGlobalConfig, dprint.ensureStableFormat). Otherwise clicking the button would restart every dprint process.

The Dprint: Format Document (global config) and Dprint: Format Selection (global config) commands still say when no configuration file was found, since they're run explicitly.

Verification

• tsc, npm run test:unit and dprint check pass.

Not tested

• No automated test covers the new setting or the button, and the integration tests (npm test) were not run locally.