[lib] update creatorID -> unread in CreateThickRawThreadInfoInput

Summary:
[ENG-8568](https://linear.app/comm/issue/ENG-8568/logic-for-adding-a-user-user-joining-a-thick-thread)

We need to use `CreateThickRawThreadInfoInput` when creating `ADD_VIEWER_TO_THREAD_MEMBERS`, where it's complicated to retrieve `creatorID`.

`creatorID` is used only for computing `unread`, that being said we can simplify this.

Test Plan: Flow

Reviewers: tomek, inka

Reviewed By: tomek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D13181

lib/shared/dm-ops/create-sidebar-spec.js

@@ -116,7 +116,7 @@ const createSidebarSpec: DMOperationSpec<DMCreateSidebarOperation> =
           parentThreadID,
           allMemberIDs,
           roleID,
-          creatorID,
+          unread: creatorID !== viewerID,
           sourceMessageID,
           containingThreadID: parentThreadID,
         },

lib/shared/dm-ops/create-thread-spec.js

@@ -67,7 +67,7 @@ function createThickRawThreadInfo(
     parentThreadID,
     allMemberIDs,
     roleID,
-    creatorID,
+    unread,
     name,
     avatar,
     description,
@@ -107,7 +107,7 @@ function createThickRawThreadInfo(
       role: role.id,
       permissions: membershipPermissions,
       subscription: joinThreadSubscription,
-      unread: creatorID !== viewerID,
+      unread,
     }),
     repliesCount: repliesCount ?? 0,
     name,
@@ -171,7 +171,7 @@ const createThreadSpec: DMOperationSpec<DMCreateThreadOperation> =
           creationTime: time,
           allMemberIDs,
           roleID,
-          creatorID,
+          unread: creatorID !== viewerID,
         },
         viewerID,
       );

lib/types/dm-ops.js

@@ -40,7 +40,7 @@ export type CreateThickRawThreadInfoInput = {
   +parentThreadID?: ?string,
   +allMemberIDs: $ReadOnlyArray<string>,
   +roleID: string,
-  +creatorID: string,
+  +unread: boolean,
   +name?: ?string,
   +avatar?: ?ClientAvatar,
   +description?: ?string,
@@ -58,7 +58,7 @@ export const createThickRawThreadInfoInputValidator: TInterface<CreateThickRawTh
     parentThreadID: t.maybe(t.String),
     allMemberIDs: t.list(tUserID),
     roleID: t.String,
-    creatorID: tUserID,
+    unread: t.Boolean,
     name: t.maybe(t.String),
     avatar: t.maybe(clientAvatarValidator),
     description: t.maybe(t.String),