(core) allow non-owners to remove themselves from sites/workspaces/docs

Summary:
For users who cannot otherwise change access to a resource, let
them remove themselves. Implemented via the standard endpoints
as a special exception that will process a request from a user
that would otherwise be denied, if the only contents of that
request are a removal of themselves.

Users who can change access are still not permitted to change their
own permissions or to remove themselves, as a precaution against
orphaning resources.

Test Plan: extended and updated tests

Reviewers: cyprien

Reviewed By: cyprien

Subscribers: dsagal

Differential Revision: https://phab.getgrist.com/D3367

app/client/ui/HomeLeftPane.ts

@@ -204,7 +204,8 @@ function workspaceMenu(home: HomeModel, ws: Workspace, renaming: Observable<Work
       permissionData: api.getWorkspaceAccess(ws.id),
       activeEmail: user ? user.email : null,
       resourceType: 'workspace',
-      resourceId: ws.id
+      resourceId: ws.id,
+      resource: ws,
     });
   }
 
@@ -217,8 +218,8 @@ function workspaceMenu(home: HomeModel, ws: Workspace, renaming: Observable<Work
     upgradableMenuItem(needUpgrade, deleteWorkspace, "Delete",
       dom.cls('disabled', user => !roles.canEdit(ws.access)),
       testId('dm-delete-workspace')),
-    upgradableMenuItem(needUpgrade, manageWorkspaceUsers, "Manage Users",
-      dom.cls('disabled', !roles.canEditAccess(ws.access)),
+    upgradableMenuItem(needUpgrade, manageWorkspaceUsers,
+      roles.canEditAccess(ws.access) ? "Manage Users" : "Access Details",
       testId('dm-workspace-access')),
     upgradeText(needUpgrade),
   ];