dev: code improvements and minor performance upgrades (#2201)

* dev: remove len for empty comparison

* dev: using in instead of multiple ors

* dev: assign expression to empty variables

* dev: use f-string

* dev: remove list comprehension and use generators

* dev: remove assert from paginator

* dev: use is for identity comparison with singleton

* dev: remove unnecessary else statements

* dev: fix does not exists error for both project and workspace

* dev: remove reimports

* dev: iterate a dictionary

* dev: remove unused commented code

* dev: remove redefinition

* dev: remove unused imports

* dev: remove unused imports

* dev: remove unnecessary f strings

* dev: remove unused variables

* dev: use literal structure to create the data structure

* dev: add empty lines at the end of the file

* dev: remove user middleware

* dev: remove unnecessary default None

apiserver/plane/api/urls_deprecated.py

@@ -28,7 +28,6 @@ from plane.api.views import (
     ## End User
     # Workspaces
     WorkSpaceViewSet,
-    UserWorkspaceInvitationsEndpoint,
     UserWorkSpacesEndpoint,
     InviteWorkspaceEndpoint,
     JoinWorkspaceEndpoint,