Design for integrating kopia with kanister (#1482)

* Draft design for integrating kopia with kanister

* Update the kopia.io link

* Minor updates in the document

* Address review comments

* Address reviewer comments

* minor updates to the introduction

* Update problem statement and goals

* Update scope of the design

* Add backward compatibility and user experience

* Update design introduction

* Rephrasing Problems section to motivation

* Rephrase the backward compatibility Kopia Repository Server

* Rephrase the question in backward compatibility

* Add high-level diagram for integrating kopia in kanister

* Remove images and apply suggestions

* Update design/kanister-kopia-integration/kanister-kopia-integration.md

* Add additional items for Kopia integration design

Signed-off-by: Ivan Sim <ivan.sim@kasten.io>

* Add info on server replicas count and handling the credential changes

Signed-off-by: Ivan Sim <ivan.sim@kasten.io>

* Clarify on updating access users list

Also remove service account-based access approach, due to RBAC concerns

Signed-off-by: Ivan Sim <ivan.sim@kasten.io>

* Add repo server CRD and consolidate files

* Line wrap to 80 chars

* Address Ivan's reviews

* Note about the Kanister Functions

Signed-off-by: Ivan Sim <ivan.sim@kasten.io>
Co-authored-by: Pavan Navarathna Devaraj <6504783+pavannd1@users.noreply.github.com>
Co-authored-by: Ivan Sim <ivan.sim@kasten.io>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
Co-authored-by: Prasad Ghangal <prasad.ghangal@gmail.com>