feat(openchallenges): show role of organizations in Contributors section

[vpchung]

Part 1 for #2222 , focusing on the UI

Fixes #2222

Changelog

• Add 3 categories to the "Contributors" section of a challenge

Preview

[tschaffter]

Thanks for implementing this feature! I'm going to make a 3-min video soon that introduces OC and I thought how cool it would be to have it implemented by then.

Here I come again about grouping elements together. 😛

The space between the subtitle and the content should be smaller than the space between the content and the next subtitle.

[tschaffter]

See comment above.

EDIT: What do you think about not displaying empty sections?

EDIT: We prefer to keep the empty sections for a few months to promote challenge organizers to provide the missing information. It has also been discussed that "Not available" should be treated differently than "no sponsor", for instance (valid value) (future work).

[tschaffter]

Converting to Draft as @vpchung and I are contributing to this PR.

[tschaffter]

Here is an example of challenge that includes all three types of contributions (for testing): http://localhost:4200/challenge/8?tab=contributors

Note
The link does not lead directly to the contributions tab (bug).

[tschaffter]

Component Logic Preview

Note
Organizations are ordered by the number of challenges they have contributed to.

@vpchung The component logic is ready.

[vpchung]

UI update:

[rrchai]

LGTM!