fix: Eliminate N+1 API calls for interactive templates in flow editor

[sentry]

Summary

This PR addresses the N+1 API call issue observed on /flow/configure/* pages, specifically for interactive templates.

Problem:
When loading a flow in the editor, the underlying @nyaruka/temba-components library makes individual HTTP GET requests to /flow-editor/interactive-templates/{id} for each interactive template referenced in the flow. This results in a significant number of redundant network calls, impacting performance.

Solution:
Introduces a setupInteractiveTemplateCache function in FlowEditor.helper.tsx that patches window.fetch. This interceptor works as follows:

1. The first time a request to interactive-templates/{id} is made, it triggers a single network call to the list endpoint (/flow-editor/interactive-templates) to fetch all available templates.
2. These templates are then stored in an in-memory cache, keyed by their ID.
3. Subsequent individual requests for interactive-templates/{id} are served directly from this cache, eliminating further network calls.

This approach significantly reduces network overhead and improves the loading performance of the flow editor when dealing with multiple interactive templates. The window.fetch patch is properly cleaned up when the component unmounts, following the pattern established by setAuthHeaders.

Test Plan

1. Navigate to a flow configuration page (e.g., /flow/configure/some-flow-id) that contains multiple interactive templates.
2. Open your browser's developer tools and go to the 'Network' tab.
3. Observe the network requests made when the page loads.
4. Verify that only one network request is made to /flow-editor/interactive-templates (the list endpoint).
5. Confirm that no subsequent individual GET /flow-editor/interactive-templates/{id} requests are made over the network for each template, as they should be served from the cache.
6. Reload the page and repeat the observation to ensure consistent caching behavior.

Fixes GLIFIC-FRONTEND-13G

[github-actions]

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[cypress]

Glific    Run #9899

Run Properties:   Passed #9899  •  998f81389a ℹ️: Merge db11207b7984ad629af77effdfa0d7cd1a985c3f into 9200718f48bc5bdd78560eec871e...

Project	Glific
Branch Review	seer/fix/n-plus-1-interactive-templates
Run status	Passed #9899
Run duration	06m 45s
Commit	998f81389a ℹ️: Merge db11207b7984ad629af77effdfa0d7cd1a985c3f into 9200718f48bc5bdd78560eec871e...
Committer	sentry[bot]
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Test results
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Flaky	0
Pending	0
Skipped	0
Passing	32
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