Return only remote_development enabled agents on cluster agent queries without breaking existing endpoints
<!--IssueSummary start-->
<details>
<summary>
Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards.
</summary>
- [Work on this issue](https://contributors.gitlab.com/manage-issue?action=work&projectId=278964&issueIid=546426)
- [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=546426)
</details>
<!--IssueSummary end-->
MRs:
gitlab-org/gitlab!192329+
<!-- NOTE: For context on MR heading, see:
https://handbook.gitlab.com/handbook/engineering/development/dev/create/remote-development/index.html#relationship-of-issues-to-mrs
-->
## Description
As per Product input, in [this comment](https://gitlab.com/gitlab-org/gitlab/-/issues/536924#note_2523469463 ), we should be able to return organization workspaces cluster agents that have enabled remote development. This is to support the [current proposed UI ](https://gitlab.com/gitlab-org/gitlab/-/issues/513370/designs/Admin_area_-__General_-__Expanded_-__Filtering.png).
The existing [namespace](https://docs.gitlab.com/api/graphql/reference/#namespaceworkspacesclusteragents)/[group](https://docs.gitlab.com/api/graphql/reference/#groupworkspacesclusteragents) agent APIs will also be adapted to return enabled agents, however, this will require maintaining the deprecated but unremoved endpoints to still behave as is (return enabled and disabled), i.e:
- https://docs.gitlab.com/api/graphql/reference/#groupremotedevelopmentclusteragents
- https://docs.gitlab.com/api/graphql/reference/#namespaceremotedevelopmentclusteragents
Pending breaking change removal
<!-- TODO: What kind of issue is this? Please uncomment and include one of the following:
/label ~"type::feature"
/label ~"type::bug"
/label ~"type::maintenance"
-->
<!-- OPTIONAL: Is this a feature/enhancement?
- Please describe the impact this feature/enhancement will have on the user experience and/or the product as a whole.
- Provide a user story to illustrate the use case for this feature/enhancement. Include examples to help communicate the intended functionality.
-->
<!-- OPTIONAL: Is this a bug? Please uncomment and include the following:
- **Current behavior:**
- **Expected behavior:**
- **Steps to reproduce:**
- **Additional information:** please include VSCode version, browser dev tool logs, etc that might be helpful to debug the issue!
-->
## Acceptance criteria
- [x] Restrict organization cluster agents that have remote development enabled only
- [ ] Restrict the experimental namespace/group cluster agents API to return remote development enabled only
- [ ] Maintain the deprecated namespace/group API to return both disabled/enabled agents pending deprecations.
## Implementation plan
### Org Path
- Remove dependency on `NamespaceClusterAgentFilter` for the filter parameter
- Introduce `OrganizationClusterAgentFilter` as an enum to classify `ALL` and `DIRECTLY_MAPPED` agents
- Organization `WorkspaceClusterAgents` query that takes in a compulsory `filter` parameter of type `OrganizationClusterAgentFilter`
- Maintain appropriate GraphQL feature specs and associated finder specs
### Namespce/Group API backward compatibility Path
- Configure the namespace agent finder to accept a flag of `enabled` default is false
- Give the deprecated namespace/group API its own resolver that will translate to a finder call that maintains backward compatibility
- Maintain the finder specs to adjust to the additional parameter that will make future cleanup easy
issue