[workflow] Adding channels input for bundle images in release workflow

[didierofrivia]

This PR is part of Kuadrant Operator issue Kuadrant/kuadrant-operator#244

The workflow dispatch input channels accepts comma separated values, i.e.: "stable,release". The Makefile target could be executed as:

make prepare-release \
  VERSION=0.7.0 \
  AUTHORINO_VERSION=0.14.0 \
  CHANNELS=stable,release

And it will generate, among other changes, the following:

diff --git a/bundle.Dockerfile b/bundle.Dockerfile
index 8fe9a64..5b9211f 100644
--- a/bundle.Dockerfile
+++ b/bundle.Dockerfile
@@ -5,7 +5,7 @@ LABEL operators.operatorframework.io.bundle.mediatype.v1=registry+v1
-LABEL operators.operatorframework.io.bundle.channels.v1=alpha
+LABEL operators.operatorframework.io.bundle.channels.v1=stable,release

diff --git a/bundle/metadata/annotations.yaml b/bundle/metadata/annotations.yaml
index 118a56d..39e6d57 100644
--- a/bundle/metadata/annotations.yaml
+++ b/bundle/metadata/annotations.yaml
@@ -4,7 +4,7 @@ annotations:
-  operators.operatorframework.io.bundle.channels.v1: alpha
+  operators.operatorframework.io.bundle.channels.v1: stable,release

[adam-cattermole]

These changes look good to me, results in the bundle labels being updated with the value of CHANNELS. In this case as the catalog is sqlite-based the channels are set from the bundle labels.