feat: add partialUpdateMember endpoint

[yaziine]

CLA

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

Description of the changes, What, Why and How?

This adds the ability to update channel member custom data.

Changelog

• Add partialUpdateMember endpoint

[github-actions]

Size Change: +822 B (+0.19%)

Total Size: 426 kB

Filename	Size	Change
dist/browser.es.js	92.4 kB	+190 B (+0.21%)
dist/browser.full-bundle.min.js	54 kB	+66 B (+0.12%)
dist/browser.js	93.5 kB	+187 B (+0.2%)
dist/index.es.js	92.4 kB	+189 B (+0.2%)
dist/index.js	93.6 kB	+190 B (+0.2%)

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