feat(type): use unitless line-heights

[tw15egan]

Closes #6711

Updates our type package to use a unitless line-height value

Changelog

Changed

• Modified the scss and js type scale files
• Instead of calling a carbon--rem() to set the line-height, we just set it to a unitless value
• Typos

Testing / Reviewing

Ensure the values match the website documentation, with the exception of heading-03. An issue has been made for that here carbon-design-system/carbon-website#1604

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[joshblack]

The changes look good code-wise, although from the percy snapshots it seems like there might be some unexpected line height changes? I'm not sure how the line-height value was computed but for productive-heading-06 it seems like the font-size is 42px and the line-height was set to 3.125 which I believe gives us the 131.25px value line-height in that story (42px * 3.125 = 131.25)

I think the value of line-height should be computed by proportion instead of relative to the base font-size, so instead of 50px / 16px = 3.125 it'd be 50px / 42px = 1.19 for the line-height value. What do you think @tw15egan? 👀

[tw15egan]

@joshblack Ah yeah that would explain the differences... so would we need to compute that for all of them? i.e. body short 01 would be 18px / 14px = 1.285?

[joshblack]

@tw15egan yeah! Exactly.

[tw15egan]

@joshblack updated. After making these changes, I noticed there were still 29 diffs in Percy. Seems like Chrome rounds 15.94px DOWN to 15px, which was throwing off any line heights that were set to 1.33. As a result, I bumped any 1.33 values up to 1.34 👍