Apply form-control variables to create consistent scaling

[sebnitu]

What changed?

This PR aligns form-controls sizing and scale by applying from-control variables. This allows form-controls to adjust their size based on the font-size property. This also removes a lot of previously used variables for controlling form-control size such as padding and line-height.

This is achieved by refactoring the css.get function to allow passing undefined properties as long as a fallback is also provided:

// Example usage
font-size: css.get("button", "font-size", css.get("form-control-font-size"));

// CSS output
font-size: var(--vb-button-font-size, var(--vb-form-control-font-size));

In the above example, --vb-button-font-size is not defined, but --vb-form-control-font-size is so it's value will be used while still allowing overriding the value whenever --vb-button-font-size is defined. Applying this methodology to all form-controls also means the size of all form-controls can be set by defining --vb-form-control-font-size.

Lastly, this PR fixes root output issues with the vrembem package and includes missing root exports in both base and utility components. When using vrembem in a Sass environment, it's important to import all base components before running any root css.output() calls. Here's an example of how a manifest might look:

// Import all base vrembem components.
@use "vrembem/base";

// Import all my custom components and project specific styles.
@use "./global";
@use "./my-component";
...

// Finally, run the root import to output all custom properties that have been set.
@use "vrembem/root";