classifies "width-height" web feature

[ChrisC]

Reference: https://github.com/web-platform-dx/web-features/blob/main/features/width-height.yml

Note: The width and height CSS properties establish the preferred physical dimensions of an element. This classification includes tests for the auto value, percentage values, and property behavior across various contexts.

Search strategy: Searched for tests linking to "propdef-width", "propdef-height", "the-width-property", "the-height-property", and "preferred-size-properties".

WEB_FEATURES.yml files created/edited:
✅ css/CSS2/normal-flow/WEB_FEATURES.yml - CSS2.1 width/height tests (195 files)
✅ css/CSS2/css1/WEB_FEATURES.yml - CSS1 width/height tests (12 files)
✅ css/CSS2/positioning/WEB_FEATURES.yml - Absolute positioning width/height tests (4 files)
✅ css/CSS2/page-box/WEB_FEATURES.yml - Page container tests (4 files)
✅ css/CSS2/visudet/WEB_FEATURES.yml - Height percentage tests (3 files)
✅ css/CSS2/csswg-issues/submitted/css2.1/WEB_FEATURES.yml - Anonymous boxes test (1 file)
✅ css/css-sizing/WEB_FEATURES.yml - Percentage height test (1 file)
✅ css/css-sizing/parsing/WEB_FEATURES.yml - Width/height parsing tests (4 files)
✅ css/css-box/parsing/WEB_FEATURES.yml - CSS Box 3 parsing tests (4 files)
✅ svg/geometry/parsing/WEB_FEATURES.yml - SVG sizing properties test (1 file)

Excluded:

• Float behavior (3 files): Primary focus is float shrink-to-fit, not width property
• Anonymous boxes/pagination (4 files): Primary focus is anonymous boxes/pagination behavior
• Run-in display (2 files): Primary focus is run-in display, not width/height properties
• Stretch keyword (2 files): Primary focus is stretch keyword
• Interpolate-size (4 files): Already mapped to interpolate-size feature
• css/css-sizing/animation/: Width/height animation tests (5 files)
• Other features (4 files): Flexbox quirks, multicol, tables, calc() - width/height used incidentally

Originally submitted as part of b26f616