feat: add snjs package

packages/snjs/lib/Services/Settings/SettingsClientInterface.ts

@@ -0,0 +1,16 @@
+import { SettingName, SensitiveSettingName, EmailBackupFrequency } from '@standardnotes/settings'
+import { SettingsList } from './SettingsList'
+
+export interface SettingsClientInterface {
+  listSettings(): Promise<SettingsList>
+
+  getSetting(name: SettingName): Promise<string | undefined>
+
+  getDoesSensitiveSettingExist(name: SensitiveSettingName): Promise<boolean>
+
+  updateSetting(name: SettingName, payload: string, sensitive?: boolean): Promise<void>
+
+  deleteSetting(name: SettingName): Promise<void>
+
+  getEmailBackupFrequencyOptionLabel(frequency: EmailBackupFrequency): string
+}