Add Compose demo for LineHeightStyle.Mode.PerLine

Adds an interactive Compose demo comparing `LineHeightStyle.Mode.Minimum` with the new `LineHeightStyle.Mode.PerLine` behavior.

Shows how `PerLine` prevents line overlapping when mixing font sizes in a paragraph.

TAG=agy
CONV=6a150c76-4f35-43bb-8f3d-bb17402fa8e9

Bug: 520107988
Test: ./gradlew :compose:foundation:foundation:integration-tests:foundation-demos:assembleRelease
Relnote: "N/A"
Change-Id: I5d1bd970aa286a11d792345ff11680f2174a2a2c