Add support for mail grantees

[aduffeck]

This PR implements sharing with email addresses as per #2516

Depends on opencloud-eu/reva#616

httpyacs 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)    ;
}}

### Get viewer role
# @name roles
GET {{host}}/graph/v1beta1/roleManagement/permissions/roleDefinitions
Authorization: Basic {{username}}:{{password}}
?? status == 200


### Invite a single guest using an email address
POST {{host}}/graph/v1beta1/drives/{{personaldrive.id}}/items/{{$global.fileid}}/invite
Authorization: Basic {{username}}:{{password}}
Content-Type: application/json

{
    "recipients": [
        {
            "objectId": "some.guest@example.com",
            "@libre.graph.recipient.type": "mail"
        }
    ],
    "roles": ["{{roles[0].id}}"]
}


### List existing shares
# @name listshares
GET {{host}}/graph/v1beta1/drives/{{personaldrive.id}}/items/{{$global.fileid}}/permissions
Authorization: Basic {{username}}:{{password}}
?? status == 200
{{
    const shares = response.parsedBody.value;
    $global.shareId = shares[0].id;
}}

### Update permission role
PATCH {{host}}/graph/v1beta1/drives/{{personaldrive.id}}/items/{{$global.fileid}}/permissions/{{$global.shareId}}
Authorization: Basic {{username}}:{{password}}
Content-Type: application/json

{
    "roles": ["{{roles[0].id}}"]
}
?? status == 200

[sonarqubecloud]

Quality Gate failed

Failed conditions
13.5% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud