API can't create Email relationships

[gahenderson]

Issue

When looking to create a relationship between emails and other modules (tested with Accounts and Leads) this will fail, claiming to not find the link field.

Expected Behavior

A relationship is added between the records, and a success message is returned via the API

Actual Behavior

No link is created and the following error is returned in the body:

        "status": 400,
        "title": null,
        "detail": "Link field has not found in Lead to determine relationship for Email"
    } ```

#### Possible Fix
The bug appears to happen when the API BeanManager searches for the linked field name (getLinkedFieldName). There are 2 link names in the relationships table in the database and it retrieves the wrong one (this depends on which order they are returned by the database which I believe is ordered by id).

#### Steps to Reproduce
1. Create or find a pre-existing email & note its ID
2. In Postman, send 'Create Relationship' HTTP POST request eg
   ``` <suite host>/Api/V8/module/Emails/cd9fc6e2-3391-1c73-3183-5dd6a8ac56ef/relationships ```
with a body similar to
   ``` {
  "data": {
    "type": "Leads",
    "id": "18740080-7fbd-4966-f401-5d67daa9c6bd"
  }
} ```

#### Context
Looking to archive an email against the relevant record but this is not possible

#### Your Environment
OS: Ubuntu 18.04.3 LTS
Browser: Chrome 77.0.3865.90 64Bit
SuiteCRM: 7-11-8
Postman: 7.10.0 x64