migrating webapp/channels/src/tests files to typescript (#25016)

* migrating webapp/channels/src/tests files to typescript

* Fixing linter errors

* Fixing the setup config of the jest.config.js

* Fixing CI

* fix linter errors

* Fixing tests

* fixing ci

webapp/channels/jest.config.js

@@ -41,7 +41,7 @@ const config = {
         'node_modules/(?!react-native|react-router|p-queue|p-timeout|@mattermost/compass-components|@mattermost/compass-icons)',
     ],
     setupFiles: ['jest-canvas-mock'],
-    setupFilesAfterEnv: ['<rootDir>/src/tests/setup.js'],
+    setupFilesAfterEnv: ['<rootDir>/src/tests/setup.ts'],
     testEnvironment: 'jsdom',
     testTimeout: 60000,
     testURL: 'http://localhost:8065',