[MM-40406] Add more singletons, refactor main.ts into pieces, add tests and some cleanup + tests for additional coverage (#1890)

* Refactor main.ts dependencies into singleton pattern

* Split main.ts into testable pieces, some other refactoring for singleton pattern

* Unit tests for main/app/app

* Unit tests for main/app/config

* Unit tests for main/app/initialize

* Unit tests for main/app/intercom

* Unit tests for main/app/utils

* Add some more tests to get to 70% coverage

* Fix for linux

* Fix for alternate data dir paths

* Fix E2E test

.eslintrc.json

@@ -72,7 +72,6 @@
                 "scripts/check_build_config.js",
                 "LICENSE.txt",
                 "src/utils/util.ts",
-                "src/main/main.ts",
                 "src/main/contextMenu.ts",
                 "src/renderer/updater.tsx",
                 "src/main/badge.ts",