[main] implemented update subscription

[knative-prow-robot]

This is an automated cherry-pick of #427

Fixes updating of existing subscriptions on dispatcher: retryConfig, url, reply, deadLetter

[codecov]

Codecov Report

Merging #429 (c2c440e) into main (0c051c9) will increase coverage by 6.46%.
Report is 5 commits behind head on main.
The diff coverage is 67.74%.

@@            Coverage Diff             @@
##             main     #429      +/-   ##
==========================================
+ Coverage   38.97%   45.44%   +6.46%     
==========================================
  Files          29       29              
  Lines        1919     1941      +22     
==========================================
+ Hits          748      882     +134     
+ Misses       1125     1004     -121     
- Partials       46       55       +9     

Files	Coverage Δ
pkg/channel/jetstream/dispatcher/dispatcher.go	50.61% <81.81%> (+25.50%)	⬆️
pkg/channel/jetstream/dispatcher/reconciler.go	57.29% <33.33%> (+29.18%)	⬆️

... and 2 files with indirect coverage changes

[creydr]

/lgtm

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: creydr, knative-prow-robot

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [creydr]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment