Move exporter code into crane

[dmartinol]

Develop configurable crane plugin(s) to export the same kustomize package that is today generated by the Golang app

• create issue in crane repository
• discuss implementation with project contributors
• develop changes
• PR
• merge
• generate new release
• remove implementation from Saasi exporter
• validate changes

[dmartinol]

Started discussion on slack channel

[dmartinol]

Prepared code changes on forked repo:
migtools/crane@main...dmartinol:crane:#148-cluster-scoped-rbac

Waiting approval from contributors to move on with the PR

[dmartinol]

Created code changes for Saasi in related branch:
main...50-move-exporter-code-into-crane

Note: it assumes to have the before mentioned cluster-scoped-rbac feature in crane export, otherwise it would not work

[dmartinol]

PR in crane repository:
migtools/crane#149

Agreed with other contributors to track another issue to clarify that, even if the filtering logic implemented there would be more suitable for the transform step instead of the export one, the current limitations of the tool would lead to very low performance, so for now we accept the change and track the possible enhancement

[dmartinol]

PR in SaaSi:
#64