Define RPC payload typing in `cross-origin-rpc`

Move the typing for the parameter passed to the `changeFocusModeUser`
RPC call into `cross-origin-rpc` and expand in preparation for
supporting group filtering.

src/sidebar/cross-origin-rpc.js

 import warnOnce from '../shared/warn-once';
 
+import { normalizeGroupIds } from './helpers/groups';
+
+/**
+ * @typedef FocusUserInfo
+ * @prop {string} [userid]
+ * @prop {string} [username]
+ * @prop {string} [displayName] - User's display name
+ * @prop {string[]} [groups] - A list of group IDs that correspond to the
+ *   focused user's list of groups. This is assumed to represent a subset
+ *   of the `groups` currently loaded in the store. Each entry in this array
+ *   may be either an `id` (a.k.a. `pubid`) OR a `groupid`. These should be
+ *   normalized to `id`s (`pubid`s) before use with the store.
+ */
+
 // Array to keep track of pre-start requests
 let preStartQueue = [];
 

src/sidebar/store/modules/filters.js

@@ -22,16 +22,14 @@ import { createStoreModule } from '../create-store';
  */
 
 /**
- * Structure of focus-mode config, provided in settings (app config)
- * @typedef FocusConfig
- * @prop {FocusUserConfig} user
+ *
+ * @typedef { import('../../cross-origin-rpc').FocusUserInfo } FocusUserInfo
  */
 
 /**
- * @typedef FocusUserConfig
- * @prop {string} [userid]
- * @prop {string} [username]
- * @prop {string} displayName - User's display name
+ * Structure of focus-mode config, provided in settings (app config)
+ * @typedef FocusConfig
+ * @prop {FocusUserInfo} user
  */
 
 /**
@@ -153,7 +151,7 @@ const actions = actionTypes(reducers);
 /**
  * Change the focused user filter and activate focus
  *
- * @param {FocusUserConfig} user - The user to focus on
+ * @param {FocusUserInfo} user - The user to focus on
  */
 function changeFocusModeUser(user) {
   return { type: actions.CHANGE_FOCUS_MODE_USER, user };