*.test.ts files should be in separate folder (forgive if this is duplicate issue)

[ghost]

Forgive me since I can't read Swedish (so this may be a duplicate issue):

• All tests should be in separate folder than main source code files, to make maintenance easier

Example: https://github.com/kolplattformen/skolplattformen/tree/main/libs/api-skolplattformen/lib

• Contains source files and tests