fix: fix channel.membership type

[myandrienko]

We had a separate type for channel.membership which seemed to be incomplete and different from the type of channel.members[i].

In this PR:

1. Replace ChannelMembership type with ChannelMemberResponse everywhere, since it's supposed to be the same type (see backend types: [1] and [2]).
2. Keep ChannelMembership for reverse compatibility, but deprecate it and make it an alias for ChannelMemberResponse.

[github-actions]

Size Change: +73 B (+0.02%)

Total Size: 369 kB

Filename	Size	Change
dist/browser.es.js	79.6 kB	+17 B (+0.02%)
dist/browser.js	80.6 kB	+20 B (+0.02%)
dist/index.es.js	79.6 kB	+17 B (+0.02%)
dist/index.js	80.7 kB	+19 B (+0.02%)

ℹ️ View Unchanged

Filename	Size
dist/browser.full-bundle.min.js	48.2 kB

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