Add a setting disallowing access to all namespaces

[chmouel]

With the cluster resolver we allow access to all namespaces by default if empty. This is not always desirable and we should have a way to only allow explicitly the namespaces that are allowed.

Let the user configure the blocked-namespaces setting to * to disallow all namespaces by default and only allow access to namespaces with the allowed-namespaces setting.

Changes

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Release Notes

Add special value `*` to the blocked-namespace setting for the cluster-resolver to disallow by default all namespaces and only allow the namespaces explicitly listed in `allowed-namespace` setting.

[vdemeester]

@chmouel any reason to not change the default value as well ?

[tekton-robot]

The following is the coverage report on the affected files.
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File	Old Coverage	New Coverage	Delta
pkg/resolution/resolver/cluster/resolver.go	82.7%	83.3%	0.7

[tekton-robot]

The following is the coverage report on the affected files.
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File	Old Coverage	New Coverage	Delta
pkg/resolution/resolver/cluster/resolver.go	82.7%	83.3%	0.7

[chmouel]

@chmouel any reason to not change the default value as well ?

I didn't think it's fair to our users to change the default behavior unless it's decided to be a security issue in #7236 then i guess we should change the default to star...

We could as well make empty value ("") in blocked-namespaces disallowing everything by default and allowed-namespaces == * allow everything if we wanted too... which does seem a tiny bit more logical but either way i am fine..

[tekton-robot]

The following is the coverage report on the affected files.
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File	Old Coverage	New Coverage	Delta
pkg/resolution/resolver/cluster/resolver.go	82.7%	83.3%	0.7

[chmouel]

/kind feature

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-pipeline-go-coverage-df to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/resolution/resolver/cluster/resolver.go	82.7%	83.3%	0.7

[tekton-robot]

The following is the coverage report on the affected files.
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File	Old Coverage	New Coverage	Delta
pkg/resolution/resolver/cluster/resolver.go	82.7%	83.3%	0.7

[vdemeester]

cc @abayer

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-pipeline-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/resolution/resolver/cluster/resolver.go	82.7%	83.3%	0.7

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-pipeline-go-coverage-df to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/resolution/resolver/cluster/resolver.go	82.7%	83.3%	0.7

[tekton-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: vdemeester, Yongxuanzhang

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[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-pipeline-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/resolution/resolver/cluster/resolver.go	82.7%	83.3%	0.7

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-pipeline-go-coverage-df to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/resolution/resolver/cluster/resolver.go	82.7%	83.3%	0.7

[vdemeester]

/lgtm