Modal - width and max-width can be set via CSS vars

[mcoker]

We have vars for modal width and max-width in core:

--pf-c-modal-box--Width
--pf-c-modal-box--MaxWidth

Ideally we would set those inline, which allows this rule to continue to work, for example, the css property that changes the width/size changes from width to something like flex-basis or whatever, if we want to make some other kind of adjustment along with whatever the user has specified as their custom width, etc.

Here's the current code:

patternfly-react/packages/react-core/src/components/Modal/ModalContent.tsx

Lines 80 to 81 in 5d1af98

	/** Default width of the modal. */
	width?: number | string;

patternfly-react/packages/react-core/src/components/Modal/ModalContent.tsx

Line 155 in 5d1af98

const boxStyle = width === -1 ? {} : { width };

patternfly-react/packages/react-core/src/components/Modal/ModalContent.tsx

Lines 174 to 176 in 5d1af98

	<ModalBox
	id={boxId}
	style={boxStyle}