fix(main): still load tsconfig-paths-webpack-plugin when baseUrl misses from tsconfig

[sverweij]

Description

1. still load the tsconfig-paths-webpack-plugin when the baseUrl isn't defined and pass it ./ for baseUrl as a default path in those cases
2. when the baseUrl is defined pass undefined as baseUrl to tsconfig-paths-webpack-plugin, so the plugin will read the baseUrl from

Motivation and Context

Provides a workaround for dividab/tsconfig-paths-webpack-plugin#99; fixes #818

When dividab/tsconfig-paths-webpack-plugin#105 lands the second part of this PR should be reverted to keep the code as simple as possible

How Has This Been Tested?

• green ci
• additional & adapted automated tests

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Documentation only change
• Refactor (non-breaking change which fixes an issue without changing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• 📖

  • My change doesn't require a documentation update, or ...
  • it does and I have updated it

• ⚖️

  • The contribution will be subject to The MIT license, and I'm OK with that.
  • The contribution is my own original work.
  • I am ok with the stuff in CONTRIBUTING.md.