Api v2 cases put

[c8y3]

Updated documentation with:

• PUT /api/v2/cases/{case_identifier}
• endpoints at /api/v2/cases/{case_identifier}/iocs/{identifier}
• endpoints at /api/v2/cases/{case_identifier}/assets/{identifier}
• endpoints at /api/v2/cases/{case_identifier}/tasks/{identifier}
• the missing endpoints from Case Object IDs iris-web#549 (GET /manage/tlp/list and GET /manage/event-categories/list)
• GET /manage/severities/list

There are many endpoints which were recently added to the implementation, which are not documented yet. This is done on purpose, as I feel we need to discuss them first (they do not seem to be consistent with the rules we are trying to follow for API v2):

• implementation of GET /api/v2/alerts does not adhere to the conventions (return value for paginated data: field alerts should be field data)
• implementation of GET /api/v2/cases/{identifier}/assets does not adhere to the conventions (return value for paginated data: field assets should be field data, spurious field state, missing total, last_page, current_page and next_page)
• I am not sure we want /api/v2/login, /api/v2/logout and /api/v2/whoami
• implementation of GET /api/v2/context/search-cases (verb in URL)
• implementation of POST /api/v2/context/set (verb in URL)
• GET /api/v2/dashboard/cases/list does not adhere to the conventions (verb in URL)
• Why do we need GET /api/v2/dashboard/cases/list? Shouldn't we be using the cases resource: GET /api/v2/cases with the right parameters
• Same with GET /api/v2/dashboard/tasks/list (and maybe GET /api/v2/dashboard/reviews/list)