feat: add typescript support for custom channel member fields

[MartinCupela]

Goal

Provide typescript support for querying by and upserting custom member fields.

Issue

https://stream-io.atlassian.net/browse/PBE-6326?atlOrigin=eyJpIjoiMWEzMmIzYTllOWNjNGYwNGI2ZTNjOWFmODhlYThhZGIiLCJwIjoiaiJ9

[github-actions]

Size Change: +407 B (+0.09%)

Total Size: 458 kB

Filename	Size	Change
dist/browser.es.js	99.7 kB	+92 B (+0.09%)
dist/browser.full-bundle.min.js	56.6 kB	+33 B (+0.06%)
dist/browser.js	101 kB	+93 B (+0.09%)
dist/index.es.js	99.8 kB	+94 B (+0.09%)
dist/index.js	101 kB	+95 B (+0.09%)

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