feat(moderation): add custom check API

[varbhat]

CLA

• I have signed the Stream CLA (required).
• Code changes are tested

Description of the changes, What, Why and How?

Custom Check API was added to the Stream Moderation. This Commit/PR adds support for it in the js SDK.

Changelog

• Add Custom Check API support

[github-actions]

Size Change: +1.35 kB (+0.29%)

Total Size: 463 kB

Filename	Size	Change
dist/browser.es.js	101 kB	+321 B (+0.32%)
dist/browser.full-bundle.min.js	57 kB	+69 B (+0.12%)
dist/browser.js	102 kB	+322 B (+0.32%)
dist/index.es.js	101 kB	+318 B (+0.32%)
dist/index.js	102 kB	+323 B (+0.32%)

_{compressed-size-action}