fix: Add missing createChannels mock.

[NathanP-7West]

Hi there,

Just a minor addition to the jest-mock for the react-native package.
The createChannels method was missing a mock implementation, which was a bit of a head-scratcher in tests until I tracked it down to here.

Cheers.

[CLAassistant]

All committers have signed the CLA.

[mikehardy]

Nice one - thank you!
approved the CI run and assuming it's green I'll merge and it'll be in the next release, much appreciated

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.08%. Comparing base (75d494f) to head (1ecfd76).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1123   +/-   ##
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  Coverage   77.08%   77.08%           
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  Files          32       32           
  Lines        1727     1727           
  Branches      579      579           
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  Hits         1331     1331           
- Misses        343      395   +52     
+ Partials       53        1   -52