Add tests for minimum coverage

[echarles]

There are currently tests, these need to be updated to have a minimum coverage of the application.

For now, the tests in invoked with yarn test:js and contain 2 runnings tests (manager and browser - browser uses playwright).

yarn  test:js
ts-jest[versions] (WARN) Version 5.0.3 of typescript installed has not been tested with ts-jest. If you're experiencing issues, consider using a supported version (>=4.3.0 <5.0.0-0). Please do not report issues in ts-jest if you are using unsupported versions.
ts-jest[versions] (WARN) Version 5.0.3 of typescript installed has not been tested with ts-jest. If you're experiencing issues, consider using a supported version (>=4.3.0 <5.0.0-0). Please do not report issues in ts-jest if you are using unsupported versions.
 PASS   browser: chromium  src/__tests__/manager.spec.ts
 PASS   browser: chromium  src/__tests__/browser.spec.ts (8.229 s)
----------|---------|----------|---------|---------|-------------------
File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
----------|---------|----------|---------|---------|-------------------
All files |       0 |        0 |       0 |       0 |                   
----------|---------|----------|---------|---------|-------------------

Test Suites: 2 passed, 2 total
Tests:       2 passed, 2 total
Snapshots:   0 total
Time:        9.693 s
Ran all test suites.
 datalayer  echarles  datalayer-3  ~  …  manager   main  $    
```