Only display Invoice Type for non-regular invoices on the Invoice View

[MantisClone]

Problem

Invoice View is crowded.
Invoice Type does not seem necessary - we can omit for regular invoices, only display for non-regular invoices (like conversion)

Proposed Solution

Only display Invoice Type for non-regular invoices.
Design

Source

https://miro.com/app/board/uXjVK_t9NEA=/?moveToWidget=3458764603761740933&cot=14

[MantisClone]

After thinking about it, I no longer think we need to keep the Invoice Type field at all. It's unnecessary, even for conversion requests.

[MantisClone]

Fixed by #141