Refactor grid and flexbox layout components

[sebnitu]

What changed?

This PR is a complete overhaul of Vrembem's layout components. It removes all previous components that were primarily used as their own layout components for two more generic all purpose Grid and Flex layout components along with some shared use utilities for gap, order, justify, align and place properties.

New components

• @vrembem/grid
• @vrembem/flex

New utilities

• gap
• justify
• align
• place
• order
• spacing

Component changes

• Improved some menu component and removed some inconsistencies.
• Updated form-control var values.
• Updated base h1 font-size default.

Deprecated

• @vrembem/grid component which used flexbox and negative margins to achieve a column layout. This is now replaced with the grid layout based grid component.
• @vrembem/level component removed in favor of new flex component.
• @vrembem/media component removed in favor of new flex component.
• flex utilities. These have been incorporated into the new flex component.
• gap, gap-x and gap-y utilities have been refactored to control the gap property for grid and flexbox components. New spacing utility has been added as a replacement for vertical top margin spacing and gap-x has been deprecated.

Documentation improvements

• Added demo.js, a JS module for changing variant classes in code examples.
• Added CSS tabs slot option to <CodeExample>.
• Applied menu_size_sm modifier to "On this page" menu.
• Added the layout status to package docs.
• Updated headerAnchor module to improve styles and use icon for hash.
• Added dark/light themes to box class along with new box-alt class.
• Updated layout styles.

Fixes: #1895