Inbound/Outbound returns: naming cleanup (3h)

[lache-melvin]

Epic #2897

Is your feature request related to a problem? Please describe 👀

There is some inconsistent/confusing naming that should be resolved:

• Particularly in the frontend, Inbound Shipments and Outbound Shipments and often referred to as Inbounds and Outbounds ... now that we also have inbound and outbound returns, this could get confusing! We should make all these names explicit.

• The hook that calls generateOutboundReturnLines is just called useOutboundReturnLines, which is confusing, because elsewhere in the code, that naming pattern has meant "query the existing lines for this outbound return" rather than "generate placeholder lines and potentially include existing lines" - we should rename this to include the generate prefix

Could moving the generate_lines queries out of general and into invoice_queries here too? 🙏 And move update_lines from invoice to invoice_line mutations!

Additional context 💌

This should probably be done at the end, in case we have any other naming things that we catch along the way.

[andreievg]

Diagrams need updating and adding to internal readme.md files somewhere

[andreievg]

Refinement, it sounds like some naming may still change on front end, might be worth waiting till then: https://github.com/msupply-foundation/open-msupply/issues/4113