Clarification and Test Data for Integer/Fractional Ratios in Unit Conversions

[naronchen]

clarify how to handle integer and fractional ratios in unit conversions

Couple examples:

Fractional Ratio
decimal precision is set to 3
input unit is vertical_per_horizontal (phenomenon is slope)
0.0 → "0:1"
1.0 → "1:1"
2.0 → "1:0.5"
0.5 → "1:2"
0.333 → "1:3.003"
0.3333 → "1:3" (since 1/0.3333 = 3.0003 which gets rounded to 3.000)
0.2857 → "1:3.5"

Integer Ratio
Fractional Ratio
decimal precision is set to 3
input unit is vertical_per_horizontal (phenomenon is slope)
0.0 → "0:1"
1.0 → "1:1"
2.0 → "2:1"
0.5 → "1:2"
0.333 → "1000:3003"
0.3333 → "1:3"
0.2857 → "2:7"

https://github.com/iTwin/itwinjs-backlog/issues/1147#issuecomment-2217975255
based on this conclusion, for integer ratio, we should not always have a "1" on one side of the ratio?