Add getWarningsAndErrors() to API

[mhdirkse]

No description provided.

[mhdirkse]

Combined with ladybug-test-webapp PR wearefrank/ladybug-test-webapp#16, the code of this PR was tested as follows:

$ curl -i http://localhost/ladybug/api/report/warningsAndErrors/errorGeneratingStorage
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    52    0    52    0     0   5777      0 --:--:-- --:--:-- --:--:--  6500HTTP/1.1 200
Date: Fri, 03 May 2024 08:58:54 GMT
Content-Type: text/plain
Transfer-Encoding: chunked

A simulated error, should show up in the Ladybug GUI

This test will be automated in the Cypress tests of ladybug-frontend. This can be done if the error is properly shown in the GUI, as is the final intention of this PR.