Implement favorites

[aduffeck]

Favorites are set/unset using the graph API, and the list of favorites is managed using the search service. To filter for favorites a new is:favorite flag has been added (only works on the API level currently, the UI hasn't been adapted yet.

Note: depends on opencloud-eu/reva#554

Example httpyac for testing:

###
// @title initiate first upload
// @name upload1
{{
  $global.filename=new Buffer($random.alphabetic(50)+'.txt', 'utf-8').toString('base64')
  console.log("Generating new filename: " + $global.filename);
}}

### get personal drive
# @name personaldrive
GET {{host}}/graph/v1.0/me/drive?$select=id
Authorization: Basic {{username}}:{{password}}

### Upload file
PUT {{host}}/remote.php/dav/spaces/{{personaldrive.id}}/{{$global.filename}}
Authorization: Basic {{username}}:{{password}}
X-OC-Mtime: 1565233093
Content-Type: text/plain

uploaded content

?? status == 201

### Get file id
PROPFIND {{host}}/remote.php/dav/spaces/{{personaldrive.id}}/{{$global.filename}}
Authorization: Basic {{username}}:{{password}}
?? status == 207
{{

    const {select} = require("xpath");
    try{
        $global.fileid = select("//*[local-name(.)='id']/text()", response.parsedBody)[0].nodeValue;
    }catch(err){
        console.error(err);
    }
    console.log("id:", $global.fileid)    ;
}}

## Mark file as favorite using the graph api
POST {{host}}/graph/v1.0/me/drive/items/{{$global.fileid}}/follow
Authorization: Basic {{username}}:{{password}}
?? status == 201


## Unmark file as favorite using the graph api
DELETE {{host}}/graph/v1.0/me/drive/following/{{$global.fileid}}
Authorization: Basic {{username}}:{{password}}
?? status == 204

### Search favorites
@xpath_ns d = DAV:
REPORT {{host}}/remote.php/dav/spaces
Authorization: Basic {{username}}:{{password}}
Content-Type: application/xml
<?xml version="1.0" encoding="utf-8" ?>
<oc:search-files xmlns:d="DAV:" xmlns:oc="http://owncloud.org/ns" >
    <d:prop>*</d:prop>
    <oc:search>
        <oc:pattern>is:favorite</oc:pattern>
    </oc:search>
</oc:search-files>

[sonarqubecloud]

Quality Gate failed

Failed conditions
13.8% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud

[rhafer]

Needs rebase. Otherwise 👍