Improve KFP backend and installation instructions

[StefanoFioravanzo]

Since now we have Argo KFP and Tekton KFP both living in the same repo:

• [feature] Add the new Tekton packages into the KFP backends pipelines#10488

We need to improve the overview part, the installation flow and the architecture behind it.

cc @rimolive @Tomcli @chensun @hbelmiro @diegolovison

[hbelmiro]

This should be done after #3714.

[rimolive]

Also related. kubeflow/pipelines#10980

[varodrig]

@rimolive @hbelmiro @StefanoFioravanzo do we need to keep this open?

[varodrig]

as per @StefanoFioravanzo request we are closing this issue.

[varodrig]

/close

[google-oss-prow]

@varodrig: Closing this issue.

In response to this:

/close

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