Add a `ingresses-only` flag

[LiorLieberman]

What would you like to be added: Add a ingresses-only flag to scope the tool to only convert resources without looking for providers CRDs

Why this is needed: Provider specific support is in early stage support now with only few providers support the conversion. Users might want to scope the tool invocation to only read and convert their ingresses

/good-first-issue /help-wanted