(DOCSP-39535): Consolidate Manage Sync Subscriptions page (#3320)

## Pull Request Info - SDK Docs Consolidation

Jira ticket: https://jira.mongodb.org/browse/DOCSP-39535

*Staged Page*

- [Manage Sync
Subscriptions](https://preview-mongodbdacharyc.gatsbyjs.io/realm/DOCSP-39535/sdk/sync/manage-sync-subscriptions/)

*Page Source*

Add links to every SDK's pages where you got the SDK-specific
information:

- [C++: Manage Sync
Subscriptions](https://www.mongodb.com/docs/atlas/device-sdks/sdk/cpp/sync/sync-subscriptions/)
- [Flutter: Manage Sync
Subscriptions](https://www.mongodb.com/docs/atlas/device-sdks/sdk/flutter/sync/manage-sync-subscriptions/)
- [Java: Manage Sync
Subscriptions](https://www.mongodb.com/docs/atlas/device-sdks/sdk/java/sync/flexible-sync/)
- [Kotlin: Manage Sync
Subscriptions](https://www.mongodb.com/docs/atlas/device-sdks/sdk/kotlin/sync/subscribe/)
- [.NET: Manage Flexible Sync
Subscriptions](https://www.mongodb.com/docs/atlas/device-sdks/sdk/dotnet/sync/flexible-sync/)
- [Node.js: Manage Flexible Sync
Subscriptions](https://www.mongodb.com/docs/atlas/device-sdks/sdk/node/sync/flexible-sync/)
- [Swift: Manage Flexible Sync
Subscriptions](https://www.mongodb.com/docs/atlas/device-sdks/sdk/swift/sync/flexible-sync/)

### PR Author Checklist

Before requesting a review for your PR, please check these items:

- [x] Open the PR against the `feature-consolidated-sdk-docs` branch
instead of `master`
- [x] Tag the consolidated page for:
  - genre
  - meta.keywords
  - meta.description

#### Naming
- [x] Update Realm naming and the language around persistence
layer/local/device per [this
document](https://docs.google.com/document/d/126OczVxBWAwZ4P5ZsSM29WI3REvONEr1ald-mAwPtyQ/edit?usp=sharing)
- [x] Include `.rst` files comply with [the naming
guidelines](https://docs.google.com/document/d/1h8cr66zoEVeXytVfvDxlCSsUS5IZwvUQvfSCEXNMpek/edit#heading=h.ulh8b5f2hu9)

#### Links and Refs
- [x] Create new consolidated SDK ref targets starting with "_sdks-" for
relevant sections
- [x] Remove or update any SDK-specific refs to use the new consolidated
SDK ref targets
- [x] [Update any Kotlin API
links](https://jira.mongodb.org/browse/DOCSP-32519) to use the new
Kotlin SDK roles

#### Content
- [x] Shared code boxes have snippets or placeholders for all 9
languages
- [x] API description sections have API details or a generic placeholder
for all 9 languages
- [x] Check related pages for relevant content to include
- [x] Create a ticket for missing examples in each relevant SDK:
Consolidation Gaps epic

### Reviewer Checklist

As a reviewer, please check these items:

- [x] Shared code example boxes contain language-specific snippets or
placeholders for every language
- [ ] API reference details contain working API reference links or
generic content
- [x] Realm naming/language has been updated
- [x] All relevant content from individual SDK pages is present on the
consolidated page

---------

Co-authored-by: Kyle Rollins <115574589+krollins-mdb@users.noreply.github.com>

Author: dacharyc