Move in-memory channel dispatcher config map related code to utils

[neosab]

Actual Behavior

The in-memory channel controller writes the subscribers list from all channels into a config map that is shared with its dispatcher. This can be leveraged for other channel provisioners like kafka channel. PR #589 establishes the usefulness of this feature, however, it does not share this code with in-memory channel.

Expected behavior
The provisioners should share the dispatcher config map related code.

UPDATE:
Also need to include the changes from this comment while refactoring 14bb019#r232861763

[neosab]

/assign @matzew @neosab

@matzew Feel free to work on this.

[matzew]

ok, will take a look

[Harwayne]

/close

As of #1044, in-memory no longer uses ConfigMaps. The code has been removed. Similar code in Kafka is being removed in #1058.

[knative-prow-robot]

@Harwayne: Closing this issue.

Details

In response to this:

/close

As of #1044, in-memory no longer uses ConfigMaps. The code has been removed. Similar code in Kafka is being removed in #1058.

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