Editor: Introduces fluid typography and uses Style Engine.

This commit introduces fluid typography block supports and switches to use the Style Engine for typography and colors.

The motivation for fluid typography block supports:
>"Fluid typography" describes how a site's font sizes adapt to every change in screen size, for example, growing larger as the viewport width increases, or smaller as it decreases.
>
>Font sizes can smoothly scale between minimum and maximum viewport widths.

Typography changes introduced from Gutenberg:

* Uses the Style Engine to generate the CSS and classnames in `wp_apply_typography_support()`.
* Introduces `wp_typography_get_preset_inline_style_value()` for backwards-compatibility.
* Introduces a private internal function called `wp_get_typography_value_and_unit()`, for checking and getting typography unit and value.
* Introduces a private internal function called  `wp_get_computed_fluid_typography_value()`, for an internal implementation of CSS `clamp()`.
* Deprecates `wp_typography_get_css_variable_inline_style()`.

References:
* [WordPress/gutenberg#40332 WordPress/gutenberg PR 40332] Style Engine: add typography and color to backend
* [WordPress/gutenberg#39529 WordPress/gutenberg PR 39529] Block supports: add fluid typography

Follow-up to [53076], [52302], [52069], [51089], [50761], [49226].

Props ramonopoly, youknowriad, aristath, oandregal, aaronrobertshaw, cbirdsong, jorgefilipecosta, ironprogrammer, hellofromTonya.
See #56467.

git-svn-id: https://develop.svn.wordpress.org/trunk@54260 602fd350-edb4-49c9-b593-d223f7449a82