Remove warning on missing baseUrl, which tsconfig-paths ^4.0.0 doesn't require anymore

[sverweij]

description

• removes the check & associated warning on a missing baseUrl in tsconfig.json
• ensures plugin loading & executing commences even in the absence of a baseUrl

motivation & context

fixes #99 (& fixes #59 - which seems a duplicated of the former)

... which follows from tsconfig-paths PR #208 which makes tsconfig-paths tolerate empty/ non-existing baseUrl's,
... which is consistent with TypeScript >=4.1 behavior
... on which frameworks (like next.js) and newer projects are starting to rely

how this was tested

• green ci ( ⏳ )
• manual validation with a local install of tsconfig-paths-webpack-plugin

[jonaskello]

Released in 4.1.0