CBG-4412: Add ability to pass custom import filter into diagnostic API

[RIT3shSapata]

CBG-4412

Describe your PR here...

• Upstream PR for CBG-4411
• Adds ability to pass custom import filter into diagnostic API
• Refactor unit tests

Pre-review checklist

• Removed debug logging (fmt.Print, log.Print, ...)
• Logging sensitive data? Make sure it's tagged (e.g. base.UD(docID), base.MD(dbName))
• Updated relevant information in the API specifications (such as endpoint descriptions, schemas, ...) in docs/api

Dependencies (if applicable)

• Link upstream PRs
• Update Go module dependencies when merged

Integration Tests

• GSI=true,xattrs=true https://jenkins.sgwdev.com/job/SyncGatewayIntegration/208/
• GSI=true,xattrs=true https://jenkins.sgwdev.com/job/SyncGatewayIntegration/211/

[bbrks]

Mostly looks good 👍

[github-actions]

Redocly previews

• Admin API
• Public API
• Metric API
• Diagnostic API

[Copilot]

Pull request overview

This PR adds the ability to pass a custom import filter function to the diagnostic API's /_import_filter endpoint, allowing users to test import filter behavior with different filter implementations without modifying the database configuration.

Key changes:

• Changed the HTTP method from GET to POST for the /_import_filter endpoint to support request body
• Added support for custom import filter functions via the request body
• Refactored and expanded unit tests to cover various scenarios with and without custom import filters

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
rest/routing.go	Changed HTTP method from GET to POST for the /_import_filter endpoint
rest/diagnostic_doc_api_test.go	Removed old test function and added comprehensive table-driven tests for import filter dry run
rest/diagnostic_doc_api.go	Refactored handler to accept custom import filter in request body and improved error handling
docs/api/paths/diagnostic/keyspace-import_filter.yaml	Updated API specification to reflect POST method and document new request body parameters
db/import.go	Modified ImportFilterDryRun to accept custom import filter function and handle both default and custom filters
base/error.go	Added new error type ImportFilterDryRunError for import filter dry run errors

[bbrks]

Mostly looks good. See inline comments for specific changes/comments.

[bbrks]

LGTM 👍 thanks!