Link protests overwriting an existing item if the (sub-)nameclass is changed

**Describe the bug**
Link protests overwriting an existing item if the (sub-)nameclass is changed compared to the existing value. This can e.g. happen if editing dfn, giving it the same name as an existing tradfn (i.e. this has nothing to do with the specific use of `add` in the repro below). Link ends up with an orphaned file.

**To Reproduce**
```
]create # C:\tmp\issue
Linked: # ←→ C:\tmp\issue
⎕FX'baz' 'baz'
]add baz
Added: #.baz
baz←{baz}
]add baz
Link Warning: Cannot write baz to "C:/tmp/issue/baz.aplf" - that file defines baz
Link Warning: Writing baz to file "C:/tmp/issue/baz~2.aplf"
Added: #.baz
```
**Expected behaviour**
Silently overwrite the existing item (at least if compatible, i.e. 3/4 and 2/9).

**Desktop (please complete the following information):**
- OS: Windows
- APL version: 20.0.49263 64-bit Unicode
- `⎕SE.Link.Version`: 4.0.17