Many-to-one conversion in unit converters

[oxygen-dioxide]

Problem Statement
I often see lengths represented in "Inches, feet" format, and I want to convert them to centimeters. For example, When I see 6’5”, currently I have to convert 6’ and 5” to centimeters separately, remember the results, and add them in standard mode.

Evidence or User Insights
This is an extend of issue #243 , but for all types of physical quantity, not limited to angle.

Proposal
For any quantity type, allow inputting many source units, and convert them to one destination unit.

Goals
Converting 6’5” to centimeter quickly, without needing to remember intermediate results manually

Non-Goals

Low-Fidelity Concept

Requested Assignment

If possible, I would like to implement this.