requesthandler: Fix existing input/scene detection in create

[rjgtav]

Description

Allow re-creating an input/scene with the same name in case the previous instance has already been marked for deletion.

Motivation and Context

Deleting and re-creating an input or scene by using the same name, in consecutive requests, currently throws an "already exists", despite those items already being marked for deletion in OBS.

Here's the code snippet, using OBS Websocket's javascript bindings, for triggering the error:

import OBSWebSocket from 'obs-websocket-js';

const obs = new OBSWebSocket();
const sceneName = 'Scene';

await obs.call('RemoveScene', { sceneName });
await obs.call('CreateScene', { sceneName }); // Will throw "A source already exists by that scene name."

How Has This Been Tested?

Tested OS(s): Debian 11

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• [x] I have read the Contributing Guidelines.
• [x] All commit messages are properly formatted and commits squashed where appropriate.
• [x] My code is not on master or a release/* branch.
• [x] The code has been tested.
• [x] I have included updates to all appropriate documentation.

[tt2468]

Unfortunately, this cannot be merged. The old behavior which would allow this to happen was undefined and not intended, and as of recently, we've changed the underlying libobs functions to deduplicate names automatically. As such, in both cases, this kind of change would produce behavior which is arguably unacceptable in an API like this.