Crawler should retrieve topics from the repository

[Brend-Smits]

Topics are currently not implemented due to the Octokit API wrapper not having this functionality released yet.
We can either wait for a new release(functionality is added into the repo, just no release yet) or manually call the API for now.

After this, the hardcoded topics should be removed from the portal code.
Lines to update:
https://github.com/philips-labs/github-portal/blob/develop/Services/RepositoryService.cs#L58
https://github.com/philips-labs/github-portal/blob/develop/GithubPortal/Pages/DetailPage.razor.cs#L14-L19
https://github.com/philips-labs/github-portal/blob/develop/GithubPortal/Pages/DetailPage.razor#L104
https://github.com/philips-labs/github-portal/blob/develop/Crawler/Crawler.cs#L74

The topics should be included in the repository object.