feat: add support for the update flag endpoint

[viktorapo808]

CLA

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

Description of the changes, What, Why and How?

• Should add a support to the flag feedback endpoint that will allow users to "review" a flagged message from the React SDK client.

Changelog

[github-actions]

Size Change: +1.01 kB (+0.27%)

Total Size: 373 kB

Filename	Size	Change
dist/browser.es.js	80.6 kB	+238 B (+0.3%)
dist/browser.full-bundle.min.js	48.4 kB	+48 B (+0.1%)
dist/browser.js	81.6 kB	+243 B (+0.3%)
dist/index.es.js	80.6 kB	+239 B (+0.3%)
dist/index.js	81.6 kB	+243 B (+0.3%)

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